1988 — 1990 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Research Initiation: Three-Dimensional Vortex Dynamics Simulations of Jets and Interacting Wakes
Numerical simulations will be carried out to predict organized vortex structures in three dimensions relevant to plane wakes and round jets. Issues to be addressed are stability mechanisms and three-dimensional interactions for these vortex structures. The numerical procedure is based on Lagrangian vortex dynamics. These methods do not introduce numerical grid effects. The focus is on mechanisms which might ultimately be used to control the stability of wakes and jets.
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0.976 |
1990 — 1996 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Presidential Young Investigators Award: New Directions in Computational Fluid Dynamics @ University of Southern California |
0.976 |
1995 — 1997 |
Newton, Paul (co-PI) [⬀] Domaradzki, Julian [⬀] Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Reg: Modelling and Visualization in Aerospace Engineering @ University of Southern California
9424385 Domaradzki The Department of Aerospace Engineering at the University of Southern California will purchase computing and visualization equipment dedicated to support computational research in engineering. The equipment will be used for several research projects, including: subgrid-scale modeling based on properties of energy transfer in turbulent flows, a computational investigation of swirling jets, a study of spray dispersion in free shear flows, numerical modeling of oceanographic convection in the polar regions, wave interactions in weak turbulence models, and a study of nonlinear ring defects and their dynamics. ***
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0.976 |
1996 — 1999 |
Maxworthy, Tony [⬀] Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
A Combined Computational and Experimental Investigation of Swirling Jets @ University of Southern California
ABSTRACT Proposal Number: CTS-9523291 PI: Maxworthy This is a comprehensive and carefully integrated computational and experimental investigation of the evolution of swirling jets. These flows are of practical significance in a broad range of applications. In spite of this practical significance, the mechanisms that govern their spatio-temporal dynamics of these flows are poorly understood. Swirling jets are subjected to both shear and centrifugal instabilities and therefore exhibit a rich and varied set of disturbance modes. The generation, existence, and interaction of these mechanisms has not been investigated in any detail. It is expected that the identification, quantification, and eventual control of the governing structures by means of vortex dynamics and direct Navier-Stokes simulations, as well as experimental DPIV measurements will significantly advance the state of the art in a variety of propulsion, combustion and mixing applications.
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0.976 |
2001 — 2002 |
Leal, L. Gary Homsy, George (co-PI) [⬀] Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Parallel Computing Facility For Computational Fluid Dynamics of Complex Liquids @ University of California-Santa Barbara
Abstract CTS-0112117 E. Meiburg, Et. Al, University of California Santa Barbara
The PI together with his two colleagues at Santa Barbara request funding to purchase a mid-range parallel computer dedicated for the large scale simulations of fluid dynamics of complex liquids. The specific research areas are (1) the fluid dynamics of highly nonideal mixtures of chemical species, (2) the flow of complex fluids with microstructures, including polymer liquid crystals and suspensions, and (3) high Reynolds number flows of dilute polymers.
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1 |
2002 — 2005 |
Meiburg, Eckart Linden, Paul Rottman, James (co-PI) [⬀] |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Non-Boussinesq Gravity Currents and Two-Layer Bores @ University of California-San Diego
CTS-0209194 Paul Linden University of California San Diego
This is a collaborative research effort between UC San Diego and UC Santa Barbara to carry out experimental and computational study of gravity currents and two-layer bores in fluids of large density difference so that the usual Boussinesq approximation cannot be applied. The non-Boussinesq cases are found in many industrial flows and some chloride solutions for the low-density contrast experiments and sodium chloride solutions for the high-density contrast cases. Gross features of the flow will be recorded by shadowgraphs, and detailed velocity measurements will be made by particle tracing technique. Direct numerical simulations (DNS) willb e made for these cases at UCSB. From the understanding gained by the experimental and computational studies, models of propagation and the mixing of the currents will be formulated.
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0.975 |
2002 — 2013 |
Birnir, Bjorn (co-PI) [⬀] Petzold, Linda [⬀] Homsy, George (co-PI) [⬀] Meiburg, Eckart Maroudas, Dimitrios (co-PI) [⬀] |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Igert: Graduate Education Program in Computational Science and Engineering With Emphasis On Multiscale Problems in Fluids and Materials @ University of California-Santa Barbara
This IGERT program is structured to provide a unique Ph.D. program in interdisciplinary research and education in Computational Science and Engineering (CSE). The vision is to educate students for whom working in interdisciplinary teams is the norm, and who have the ability to acquire knowledge, ways of thinking, and perspectives from other disciplines. The proposed IGERT PhD experience is different from one in a traditional discipline, and possibly unique among CSE programs in the USA. The IGERT PhD theses will be jointly supervised, and those students with a particular disciplinary orientation will share resources, knowledge, and approaches with IGERT students with other orientations. While a typical IGERT PhD thesis will still have a strong focus in a discipline, it will contain major elements of independent creative work in other disciplines relevant to the general problem area under study. IGERT students and faculty will work together in three Focus Groups: Microscale Engineering, Complex Fluids, and Computational Materials Science, to solve a wide range of important and timely problems that depend deeply on integration of information from the smaller scales to the larger scales. These multiscale problems require a strong foundation in both engineering and the mathematical and computational sciences. The curriculum ensures depth in one area and a significant exposure to high level courses in one or more ancillary areas. It includes new courses in atomic-scale computer simulation, and computing for high performance, to specifically address the multiscale nature of the Focus Group problems and their computational requirements. An internship is required to broaden and reinforce the interdisciplinary research experience, and a required series of workshops and seminars will give IGERT students a significant exposure to important aspects of career development and ethics.
IGERT is an NSF-wide program intended to meet the challenges of educating U.S. Ph.D. scientists and engineers with the multidisciplinary backgrounds and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing innovative new models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries. In the fifth year of the program, awards are being made to twenty-one institutions for programs that collectively span the areas of science and engineering supported by NSF.
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1 |
2005 — 2010 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
A New Instability of Miscible Fluid Flows in the Stokes Regime: Linear Analysis and Direct Numerical Simulations @ University of California-Santa Barbara
PROPOSAL NO.: CTS-0456722 PRINCIPAL INVESTIGATOR: E. MEIBURG INSTITUTION: UNIV. OF CALIFORNIA SANTA BARBARA
The researchers funded under this grant will use analytical and computational tools to investigate and document the instability of two miscible fluids at low Re with annular stratification of density and viscosity in vertical and inclined tubes. Recent research has revealed the surprising result that miscible fluids, in contrast to their immiscible counterparts, are unstable according to linear stability analysis. This raises fundamental questions regarding the relationship between miscible and immiscible interfacial fluid dynamics, which are often assumed to display corresponding instabilities. Preliminary investigations of linear stability will be continued under this grant, and direct numerical simulation (DNS) studies will explore nonlinear instability. The merit of the proposed work is its investigation of this recently identified and potentially important instability of fundamental interest in fluid mechanics. The ability to predict behavior of variable viscosity and density miscible fluid flows is important for a host of processes in the chemical, pharmaceutical and oil industries. Low Reynolds number flows are particularly relevant to microfluidics applications in the biomedical and space areas. Students involved in this research will benefit by their participation with an ongoing NSF IGERT program in Computational Science and Engineering at UCSB. The PI's service at Prairie View A&M University gives strong evidence of a commitment to diversity in graduate student recruitment and education. The active involvement of foreign exchange students in research will enhance dissemination of the work.
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1 |
2007 — 2011 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Miscible Hele-Shaw Displacements: a Three-Dimensional Framework Based On the Stokes Equations @ University of California-Santa Barbara
CBET - 0651498 E. Meiburg, University of California-Santa Barbara
This research establishes a new framework for analyzing unstable miscible displacements under the influence of flow-induced dispersion. This framework, based on the three-dimensional Stokes equations, employs both nonlinear simulations as well as computational linear stability analyses. It thus supersedes the common but questionable approach of augmenting the lower-dimensional Darcy equations with simplified dispersion models of limited validity.
To establish this framework, the research focuses on the Hele-Shaw geometry frequently employed in experimental studies of unstable displacements. This geometry is relevant to numerous application areas, from lubrication problems, bearing flows, and oil displacements in fractured rocks, to small-scale MEMS devices. Variable density displacements are addressed with arbitrary angles between the nominal flow direction and the gravity vector, as are chemical reactions. The results from the Stokes investigation are subsequently employed to formulate improved Darcy-based dispersion models capable of capturing the effects of flow-induced dispersion in the Hele-Shaw geometry. In this way, this investigation contributes broadly towards advancing the understanding of the influence of flow-induced dispersion on miscible displacements.
Intellectual merit: Two- and three-dimensional, high-resolution Stokes flow simulations combined with computational linear stability analyses provide a powerful set of tools for studying the complex physics of unstable miscible displacements, and in particular how these are affected by flow-induced dispersion. They go significantly beyond the Darcy-based analyses common to date, which have to be augmented by empirical dispersion models. The new framework is employed to establish the limitations of the Hele-Shaw/Darcy analogy, and to generate the Hele-Shaw counterparts of a wide range of Darcy results.
Broader impact: The advanced understanding of flow-induced dispersion effects resulting from the proposed work enhances predictive capabilities for transport processes in porous media, and it aids in the design and optimization of a variety of flow processes of importance to the oil and chemical industries. Furthermore, the project will educate and train undergraduate and graduate students in the concepts of large-scale numerical simulations and will benefit from their association with an ongoing IGERT program in Computational Science and Engineering at UCSB.
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1 |
2009 — 2013 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
The Formation of Channels, Gullies and Sediment Waves by Turbidity Currents: a Navier-Stokes Based Framework @ University of California-Santa Barbara
Meiburg 0854338
This research will establish a novel framework for analyzing turbidity current/sediment bed interactions based on the Navier-Stokes equations, rather than the depth-averaged shallow water equations employed to date. The study focuses on the linear stability framework to provide insight into the formation of channels, gullies and sediment waves by turbidity currents. Accompanying Direct Navier-Stokes simulations will be carried out as well. Fundamental progress in this area will enhance prediction of the architecture of sediment deposits, thereby leading to more effective exploration strategies for deep-water hydrocarbon reservoirs. The study builds on a preliminary investigation by the PI into the formation of streamwise channels by turbidity currents. Specifically, a novel instability was shown to occur if the shear stress imposed by the unidirectional turbidity current base flow decays more rapidly with the distance from the sediment bed than the base flow sediment concentration. This investigation is based on the hypothesis that this newly discovered linear instability mechanism also applies to streamwise perturbations. Thus, fundamentally important questions arise regarding the convective or absolute nature of streamwise instabilities, along with their potential for giving rise to linear and nonlinear global modes. Based on the novel Navier-Stokes approach, these issues will be investigated as functions of the governing parameters. The applicability of the anticipated results to deep-water sediments will be evaluated by a close collaboration with Dr. Ben Kneller, Professor of Petroleum Geology at the University of Aberdeen and with Dr. Lesshafft at Ecole Polytechnique, for questions on questions of linear stability. Rather than averaging, the Navier-Stokes approach will resolve flow and sediment structures within the current, and thereby allow for the study of feedback mechanisms between the three-dimensional perturbation velocity and the sediment concentration field. Resolving these issues will provide insight into the spatio-temporal evolution of the vast sediment deposits at the bottom of the world?s oceans caused by phenomena such as sediment waves, ripples, dunes and antidunes. The advanced understanding of coupled turbidity current/sediment bed dynamics will improve strategies for the exploration of deep-water hydrocarbon reservoirs, for reduced drilling, and for improved recovery rates, thereby resulting in large financial savings and a reduced environmental impact. This research will furthermore train undergraduate and graduate students in computational linear stability analysis and scientific computing.
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1 |
2011 — 2014 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Gravity and Turbidity Currents Interacting With Interfaces of Free Surfaces @ University of California-Santa Barbara
1067847 Meiburg
Gravity currents form when a denser fluid propagates into a lighter one in a predominantly horizontal direction. They are frequently encountered in environmental and engineering applications. Examples are cold river outflows into a warmer lake, or a cold air front propagating into a warmer air mass. Turbidity currents represent a special class of gravity currents in which the driving force results from differential particle loading, as is the case for a sediment-laden river outflow. Turbidity currents are difficult to analyze, as they may exchange particles with surrounding fluid and/or a sediment bed by deposition or resuspension.
In a geophysical context turbidity currents - essentially submarine avalanches - play a crucial role in the global sediment cycle, as the principal means of sediment transport across the continental shelves into the deep oceans. Ancient deposits of turbidite sand, deeply buried and compacted, also form an important class of hydrocarbon reservoirs, and the host rocks for a particular type of gold deposits. In an environmental engineering context, turbidity currents are responsible for much of the sedimentation in reservoirs, with consequent loss of water storage capacity.
Frequently, gravity and turbidity currents interact with effective interfaces between stratified fluid layers, or with free surfaces. The resulting current/wave interactions give rise to a host of interesting and complex phenomena. For example, when turbidity currents form in shallow water as a result of submarine landslides, their interaction with the surface of the ocean (or lake) can result in the generation of tsunamis.
To investigate the fundamental dynamics of the above types of flows, a detailed computational investigation of turbidity currents interacting with interfaces and free surfaces will be undertaken. The simulations and experiments will provide information about the various energy conversion mechanisms active in such flows, which in turn will allow us to develop simplified theoretical models for their analysis. The proposed research will develop such models for a wide range of particle-laden flows, from turbidity currents, river plumes, pyroclastic flows and powder snow avalanches, to tsunamis generated by submarine landslides. In this way, it will benefit such diverse areas as global sediment cycle research and environmental hazard assessment.
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1 |
2011 — 2014 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Formation and Evolution of Sediment Waves: Integration of Quantitative Modeling and Field Observations @ University of California-Santa Barbara
The proposed research will extend a recently developed framework for analyzing flow/sediment bed interactions to bottom currents, debris flows and tsunamis. Differences with regard to wave orientation relative to flow direction and slope, up and downstream symmetry, direction of migration etc. will be compared in detail to corresponding field observations, in order to draw conclusions about the genesis of specific sediment wave fields. The framework for conducting both linear stability analysis and nonlinear simulations is based on the full three-dimensional Navier-Stokes equations, rather than the depth-averaged shallow water equations most commonly employed to date. A new Ph.D. post-doc will do most of the work in collaboration with the PI. The PI hopes that the proposed research will elevate the description of sediment wave formation from largely qualitative arguments to advanced, quantitative models on which we can base rigorous linear stability analyses as well as fully nonlinear simulations. In this way, it will enable us to distinguish between sediment waves generated by turbidity and bottom currents, debris flows and tsunamis, so that different sediment wave fields can be classified according to their mechanism of generation.
Broader impact: Stated broader impacts include support of quantitative, engineering-based modeling approaches within the earth science community. The work has relevance to the mission of the NSF-sponsored Community Surface Dynamics Modeling System (CSDMS). The project will also support a graduate student, as well as undergraduates and outreach to high school students.
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1 |
2013 — 2016 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Gravity Currents and Related Phenomena: a Circulation-Based Modeling Framework @ University of California-Santa Barbara
Meiburg, Eckart 1335148
Efforts to develop analytical models that predict the front velocity of gravity currents date back over several decades. The most significant of the prior models impose the conservation of mass and streamwise momentum in order to describe the current. However, in doing so they introduce an additional unknown in the form of the pressure jump across the gravity current front, so that an additional equation is required to obtain a closed system and an empirical energy argument needs to be invoked. Hence, all of them contain a certain degree of arbitrariness. Interestingly, high-resolution Navier-Stokes simulations by various authors show that the dynamics of gravity currents are determined by the conservation of mass and momentum alone, so that one should not be free to impose an additional energy constraint. Hence, a physically correct analytical gravity current model also should be based on the conservation of mass and momentum alone, and it should not invoke an energy argument. Rececently, the PI?s group showed that it is indeed possible to develop such a model, based on the vorticity formulation of the momentum conservation equation. In this approach, the pressure variable does not appear, so that it avoids the need for a closure assumption based on an empirical energy argument.
Predictions by the new model are shown to be in excellent agreement with numerical simulation results, much closer than the earlier models. These comparisons furthermore demonstrate that all of the earlier models violate the conservation of vertical momentum. The proposed research will use this novel concept of circulation-based modeling to investigate a wide range of gravity-driven flows with interfaces and free surfaces. Specifically, it will address such flows as internal bores, intrusions, stratified flows over obstacles, exchange flows over sills and particle-driven currents. Furthermore, high- resolution DNS simulations will be conducted in order to assess the range of validity of these models.
Intellectual Merit : The proposed research will develop a fundamentally new class of circulation-based models for a wide range of stratified flows. These models will be transformative in that they avoid the violation of vertical momentum inherent in existing models, along with their arbitrariness due to empirical, energy-based closure assumptions. This is accomplished by employing the vorticity form of the momentum conservation equation, thus eliminating the need for empirical closure assumptions.
Broader Impacts : The proposed research will develop conceptually new, more accurate models for a broad class of stratified flows driven by gravity. Such models serve as basis for describing a wide range of atmospheric and oceanic phenomena from sea breezes and thunderstorm outflows to powder snow avalanches and turbidity currents. In addition, they are employed in numerous technical applications involving two-phase flows. On the educational side, the proposed research project will educate and train graduate, undergraduate and high school students in the concepts of single-phase and two-phase flow modeling, large-scale numerical simulations, scientific computing, parallel computer architectures and flow visualization.
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1 |
2014 — 2017 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: Double-Diffusive Sedimentation @ University of California-Santa Barbara
CBET 1438052/1437275
This project will use theory, numerical simulation, and experiments to study the motion that is induced by instabilities in stratified liquid systems. For example, when fresh water from a river enters the ocean, concentration gradients of sediment and salt form simultaneously. Under certain conditions that can be predicted theoretically, the presence of these gradients leads to an unstable situation that induces convective motion of the sediment-laden water. Preliminary results show that this motion strongly affects the settling velocity and transport of the sediment. This project will develop a framework for analyzing motions induced by such instabilities in a variety of situations pertaining to river estuaries. However, the framework will be more broadly applicable to problems in environmental, geophysical, astrophysical, and engineering flows.
This collaborative project will use theoretical, computational, and experimental tools to explore the linear and nonlinear dynamics of double diffusive sedimentation under a wide range of conditions. Linear stability theory, direct numerical simulation, and laboratory experiments will be conducted for four basic configurations: a) a layer of sediment-laden fresh water above saline water; b) a layer of sediment-laden fresh water below saline water; c) linear concentration gradients with sediment being unstably stratified; d) linear concentration gradients with sediment being stably stratified. Effects of shear flow in the water, which is appropriate for river estuaries, will be included. The research will address a range of interesting phenomena observed in these systems including fingering instabilities, horizontal intrusions, and staircases formed in particulate systems. The proposed research will identify dominant instability mechanisms in various parameter regimes, and will provide quantitative scaling laws for double diffusive sedimentation in each case.
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1 |
2014 — 2015 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Travel Support For U.S. Participants Attending the Iutam Symposium On Multiphase Flows With Phase Change: Challenges and Opportunities, December 8 - 11, 2014, Hyderabad, India @ University of California-Santa Barbara
1417294 Meiburg
This award will provide partial support for US scientists and engineers to participate in the International Union of Theoretical and Applied Mechanics (IUTAM) Symposium on Multiphase Flow with Phase Change: Challenges and Opportunities. The symposium, which will be held December 8 - 11, 2014, in Hyderabad, India, will bring together leading experts in multiphase fluid dynamics from around the world. The symposium will feature invited and contributed research presentations as well as several poster sessions that will address important problems in multiphase systems that undergo phase change.
Multiphase flows with phase change are important in a broad range of biological, geological and industrial applications such as cloud formation, absorption of atmospheric carbon dioxide by oceans, food processing, spray combustion, and certain chemical processing operations. The emphasis on phase changes that take place in these multiphase systems makes the IUTAM symposium a unique technical conference. In addition to formal research presentations, the meeting will include discussions of future research directions, which makes participation by US scientists and engineers especially important. The award will provide support for young scientists, including students, to participate in the symposium, which will enhance the start of their science and engineering careers.
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1 |
2015 — 2018 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Uns:Collaborative Research: Multiscale Interactions Between Active Particles and Stratified Fluids During Collective Vertical Migration @ University of California-Santa Barbara
CBET - 1510607/1510615 PI: Dabiri, John/Meiburg, Eckart
This collaborative project uses experiments and numerical simulation to investigate the collective motion of small swimming organisms in water. The hypothesis underlying the project is that the collective motion of many small organisms can induce fluid motion over length scales that are much larger than the organism itself. The investigators will focus on motion in stratified fluid layers, which are commonly found in the ocean, where the top fluid layer usually is warmer and saltier than deeper fluid layers. The stratification can lead to an instability that induces fluid motion, but the presence of the swimming organisms may change conditions for the onset of the motion and affect detailed flow patterns and fluid mixing that result from the motion. Although the research focuses on motion in the ocean as an example, the insights gained from the project will apply to other particulate and multiphase systems. Both investigators will involve high school students, undergraduates and graduate students in the project. Results from the project will be used in outreach efforts to engage in the research students from groups that are traditionally underrepresented in science and engineering.
The objective of the proposal is to address experimentally and numerically the fundamental questions of multi-scale, many-body, fluid-structure interactions in stratified layers. The experiments will use a unique system that can produce on-demand vertical migrations of plankton via phototaxis in a controlled laboratory setting. A laser-guidance system will control swimming speed and swimmer spacing in collective motions. Two-dimensional particle imaging velocimetry will be used to measure flows generated by the swimmers' motion. The numerical methods implemented in the project are capable of simulating large numbers of swimming organisms with fidelity sufficient for studying details of both the near- and far-field flows. Numerical simulations will help test the possibility that collective swimming motions drive large-scale convection by modifying effective diffusivities of heat and salinity so as to induce double-diffusive convection.
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1 |
2016 — 2018 |
Luzzatto-Fegiz, Paolo [⬀] Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Iss: Quantifying Cohesive Sediment Dynamics For Advanced Environmental Modeling @ University of California-Santa Barbara
PI: Luzzatto-Fegiz, Paolo Proposal Number: 1638156
The proposed research is focused on the study of forces between particles that tend to cluster. The physical system is that of sentiments of quartz and clay particles. The advantage of conducting experiments at the International Space Station (ISS) is that it will be possible to separate the forces acting on the particles among short range (adhesive forces) and long range (cohesive forces), since one can observe the clustering dynamics over very long time scales without gravitational settling, which complicates the measurements when doing experiments on Earth. The quartz/clay system is commonly found in a wide variety of environment settings (rivers, lakes, oceans) and plays an important role in technological efforts related to deep sea hydrocarbon drilling and CO2 sequestration. Oil companies typically spend millions per well to fund exploratory drilling operations, and might require multiple exploration missions to find one good site. Results from this work could lead to a better computation model that will allow oil companies to find spots on the deep sea for drilling productive oil wells with higher precision.
The dynamics of cohesive sediment is governed by the interplay of gravitational, electrostatic and hydrodynamic forces. Earth-based laboratories do not allow for the investigation of cohesive and adhesive forces in isolation, as these are usually obscured by the effects of gravity and gravitational settling. Consequently, existing models for the dynamics of cohesive sediment have severe shortcomings, and reliable scaling laws for the magnitude of the inter-particle forces and the resulting flocculation rates and erodibility as functions of such parameters as grain size, surface size, grain material and water salinity are not available. This represents a serious impediment for predictive modeling efforts of a range of environmental systems in which cohesive sediment plays a central role, among them rivers, lakes, estuaries, the coastal ocean, fisheries and benthic habitats. Furthermore, given the high cost of deep-sea drilling, computational sediment transport models also play an increasingly important role in deep-water hydrocarbon exploration, where improved modeling tools will result in tangible economic benefits. The ISS microgravity laboratory will enable us to investigate cohesive and adhesive forces in isolation, without interference from gravity and the associated settling motion. In this way, the proposed research will allow us to formulate scaling laws for the dynamics of cohesive sediment as function of grain size, grain material and water salinity. The ISS experiments will to a large extent take advantage of an existing experimental apparatus that was employed in a previous investigation, so that the time and cost of preparing the experiments can be kept to a minimum. The scaling laws identified via the ISS experiments will subsequently be implemented into an existing, particle-resolving CFD code for detailed follow-up investigations of cohesive sediment dynamics under conditions with and without gravity. The proposed research will result in advanced predictive models for such environmental systems as rivers, lakes, estuaries, the coastal ocean, fisheries and benthic habitats, as well as for deep-sea hydrocarbon exploration and proposed CO2 sequestration strategies. On the educational side, the proposed research project will educate and train a postdoctoral scholar, as well as graduate, undergraduate and high school students in the broad concepts of microgravity fluid dynamics and computational model development.
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1 |
2016 — 2017 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Travel Support For U.S. Participants Attending the 8th International Symposium On Stratified Flows (San Diego, August 29 - September 1, 2016) @ University of California-Santa Barbara
PI: Meiburg, Eckart Proposal Number: 1630244 Institution: University of California-Santa Barbara Title: Travel Support for U.S. Participants Attending the 8th International Symposium on Stratified Flows (San Diego, August 29 - September 1, 2016)
This is a proposal to support the participation of about 20 US scientists to the 8th International Symposium on Stratified Flows that will take place in San Diego, California, between August 29th and September 1st, 2016.
This symposium is motivated by the need to understand stratified flows of different flavors and scales. Such flows are found all around us, in the atmosphere, in oceans, in rivers and in the chemical process industry. Recent developments in mathematical analysis, laboratory techniques and numerical approaches generate the need to have this symposium five years since the last one in Rome (2011). The symposium aims, in addition to the dissemination of the most recent research findings, include bringing together researchers across the world to discuss future needs in this field and to educate the next generation of young scientists. Travel and participation costs for about 20 US participants are expected to be funded with the NSF support to this conference, with priority given to younger scientists who would otherwise be unable to attend.
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1 |
2019 — 2022 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: Understanding the Physics of Flocculation Processes and Cohesive Sediment Transport in Bottom Boundary Layers Through Multi-Scale Modeling @ University of California-Santa Barbara
Due to climate change, sea level rise and anthropogenic development, coastal communities have been facing increasing threats from flooding, land loss, water quality, and other ecosystem challenges such as harmful algal blooms. Most of these pressing problems are directly or indirectly associated with sediment transport, some related to sands, but many are due to fine-grained sediments. Fine-grained sediments are cohesive and hence they transport as porous aggregates of particles, called flocs. Through their complex structures, flocs are vehicles of organic carbon, nutrients, contaminants and sometimes they can contain sand grains. Consequently, their settling velocities are very difficult to quantify. To date, most coastal/estuarine models neglect the flocculation process and adopt a constant settling velocity to estimate deposition of fine-grained sediments, which poses a considerable limitation of their predictive capability for the various challenges addressed above. In order to understand the fundamental dynamics of flocculation and their impact on fine-grained sediment resuspension and deposition, several integrated numerical simulations and optical-based laboratory observations across different scales will be carried out, including those associated with the particle size, water turbulence motions, and bottom boundary layer. Outcomes from the proposed research will be used to better equip coastal models with sediment transport capability to tackle challenges facing the coastal communities. The research findings will be widely disseminated to the coastal modeling community through participation in conferences and collaboration with the Community Surface Dynamics Modeling System (CSDMS). The open-source code to be developed and the data from the laboratory experiments will be disseminated through CSDMS and the flocculation formulation codes to be developed will be integrated into the CSDMS modeling framework via the recently released Python Modeling Toolkit (PyMT). In addition, a clinic on flocculation modeling is planned for the CSDMS annual meeting. This project supports 2 PhD students who will receive balanced training in coastal processes, fluid dynamics, high performance computing and laboratory techniques. The project also provides partial support for an early career postdoc researcher. Two undergraduate students will benefit from this project for their research on cohesive sediments. The project also strengthens collaboration with the United Kingdom and Germany on novel observational and computational tools.
The primary goal of this collaborative study is to address key challenges of cohesive sediment transport in coastal/estuarine bottom boundary layers. The study utilizes a novel particle-resolved simulation model to investigate the physics of flocculation and floc structures for heterogeneous sediments. This effort is further augmented by laboratory experiments designed to better quantify stickiness and understand flocculation of sand-mud mixtures. Using a turbulence-resolving simulation model for fine sediment transport in a wave-current bottom boundary layer, coupled with enhanced flocculation formulations to model settling velocity, the investigators will study the interplay between flocculation, resuspension and deposition of cohesive sediments in coastal/estuarine bottom boundary layers. Five hypotheses are developed to guide the experimental and modeling work which will provide insight into key small-scale processes that are difficult to resolved in coastal models. Finally, by integrating and synthesizing these research outcomes, the study will evaluate a suite of closures for the settling velocity due to flocculation, from complex to simple, to inform coastal/estuarine modeling of cohesive sediment transport at regional scale.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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1 |
2021 — 2024 |
Meiburg, Eckart |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: Two-Way Coupled Fluid/Particulate Transport in Fractured Media - Bridging the Scales From Microscopic Origins to Macroscopic Networks @ University of California-Santa Barbara
The contamination of hydrologic systems such as oceans, rivers, lakes, and aquifers with particulates has emerged as one of the most urgent environmental issues of today. Recent field data suggests a clear presence of solid contaminants, such as microplastics and pathogens, in fractured aquifers which make up a significant portion of the world's drinking water supply and in other subsurface media. Understanding and predicting particulate transport in subsurface fracture flows poses both fundamental and practical challenges, as it requires a quantitative understanding of particle/fluid transport across many length scales that range from individual particles to a network of fractures. To overcome these challenges, our research will uncover the physical origin of the coupled particle/fluid transport and its effects on the large-scale particle transport, by combining laboratory experiments, theoretical modeling, and computations both at the particle scale and the network scale. The resultant particulate transport models will greatly improve our predictive capabilities for wide-ranging subsurface processes, which include contaminant transport, geological nuclear waste disposal, hydraulic fracturing, and enhanced geothermal systems. In addition, this project will provide training opportunities for graduate students and post-docs from diverse backgrounds, as well as collaborative educational activities for high school summer interns who will gain project-based experience as part of interdisciplinary teams.
The investigators will explore and quantify the effects of two-way coupled particle/fluid motion on particulate transport in fractured media, across a wide range of scales. Towards this end, they will combine detailed laboratory experiments as well as particle-resolving simulations at the single-fracture scale, with novel upscaling approaches to the fracture network scale. Traditional particulate transport models in subsurface systems treat particles as passive scalars that do not affect the surrounding flow field, although their preliminary experiments demonstrate that particles can actively modify the fluid flow and even trigger hydrodynamic instabilities. By overcoming this deficiency of traditional models, this research project will provide the next generation of large-scale subsurface particulate transport models. Specifically, they will address three research questions: 1) the microscopic origins of the two-way coupling; 2) the hydrodynamic instabilities and dispersion in a single fracture; 3) the effects of two-way coupling on network-scale particulate transport. They will conduct systematic laboratory experiments to characterize particle-scale instabilities and collective particle behavior at the single fracture scale, which will be verified and supplemented by particle-resolving Navier-Stokes simulations of concentrated suspensions in rough fractures. The resulting data will provide effective dispersivities and stochastic rules of particulate motion that capture the two-way coupling effects on particulate transport. These results from the single fracture study will be incorporated into fracture network models, in order to assess the influence of two-way coupling on particulate transport at the network scale and to develop upscaled particulate transport models.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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