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Resolving singular forces in cavity flow: multiscale modeling from atomic to millimeter scales.
Xiaobo Nie1, Mark O Robbins, Shiyi Chen
1Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Physical Review Letters
|May 23, 2006
Summary
This study resolves singularities in multiscale fluid flow problems by combining continuum and atomistic descriptions. The research determines the force on a moving wall, revealing universal Reynolds number dependence and significant atomistic effects.
Area of Science:
- Fluid dynamics
- Multiscale modeling
- Computational physics
Background:
- Flow driven by moving walls presents a classic multiscale problem.
- Continuum equations predict singularities like logarithmic divergence and infinite vortex hierarchies.
- Previous models struggled to resolve these multiscale phenomena accurately.
Purpose of the Study:
- To develop a multiscale approach combining continuum and atomistic descriptions.
- To resolve singularities in wall-driven fluid flow.
- To determine the force on the moving wall across multiple scales.
Main Methods:
- A multiscale approach retaining atomistic descriptions in key regions was developed.
- Stress was followed over six decades of length scale.
- Simulations covered systems with characteristic scales up to millimeters and milliseconds.
Main Results:
- Singularities in the flow were resolved for the first time.
- The force on the moving wall was determined.
- A universal dependence on the macroscopic Reynolds number was found.
- Significant atomistic effects dependent on wall velocity and interactions were identified.
Conclusions:
- The developed multiscale approach successfully resolves singularities in wall-driven fluid flow.
- The findings provide a new method for determining forces in such systems.
- The study highlights the importance of atomistic effects in macroscopic fluid behavior.