To understand observations of low Reynolds number mixing and flow transitions in viscoelastic fluids, we study numerically the dynamics of the Oldroyd-B viscoelastic fluid model. The fluid is driven by a simple time-independent forcing that creates a cellular flow with extensional stagnation points. We find that at O(1) Weissenberg number these ...
Creator:
Thomases, Becca (University of California, Davis)
Created:
2010-04-13
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
Most classical and modern studies of swimming, pumping, and mixing in fluids have considered fluids that are Newtonian. All of these phenomena also take place in fluids that are viscoelastic and at low Reynolds number, and are particularly important to biology and to engineering areas such as microfluidics. I will discuss theoretical studies of ...
Creator:
Shelley, Michael J. (New York University)
Created:
2009-03-24
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
The problem of coupling microscopic and continuum-level descriptions ofcomplex fluidswhen the microscopic system exhibits slow relaxation times isconsidered. This type ofproblem arises whenever the fluid exhibits significant memory effects.The main difficultyin this type of multiscale computation is the initialization ofmicroscopic configuration...
Creator:
Mitran, Sorin (University of North Carolina, Chapel Hill)
Created:
2009-10-14
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
Direct Numerical Simulations (DNS) of turbulent viscoelastic channel flowstypically generate a tremendous volume of information (terabytes per run.Data reduction is therefore essential in order to allow for an efficientprocessing of the data, let alone its preservation for future studies.However, previous attempts, using a projection of the velo...
Creator:
Beris, Antony N. (University of Delaware)
Created:
2009-10-12
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
Keywords: Elasticity, viscoelastic instability, nonlinear transitions,drag-reducing polymersAbstract: Taylor-Couette flow (i.e., flow between concentric, rotatingcylinders) has long served as a paradigm for studies ofhydrodynamic stability. For Newtonian fluids, the rich cascadeof transitions from laminar, Couette flow to turbulent flowoccurs th...
Creator:
Muller, Susan J. (University of California, Berkeley)
Created:
2009-10-12
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
Traditional' hydrodynamic stability studies infer stability of a flow froma computation of eigenvalues of the linearized system. While this is welljustified for the Navier-Stokes equations, no rigorous result along these linesis known for general systems of partial differential equations; indeed there arecounterexamples for lower order perturbat...
Creator:
Renardy, Michael (Virginia Polytechnic Institute and State University)
Created:
2009-10-14
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
Ability to manipulate equilibrium self-assembly and dynamical self-organization in nonlinear systems is of central importance to the success of many emerging technologies. This seminar will focus on flow instability and pattern formation in complex fluids, i.e., fluids with internal microstructure such as solutions/melts of polymers, surfactant/...
Creator:
Sureshkumar, Radhakrishna (Washington University)
Created:
2009-10-12
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
This talk will provide an overview of our recent work onamplification of disturbances in channel flows ofviscoelastic fluids. Even if a standard linear stability(i.e., modal) analysis predicts that a particular flow isstable, the question of the sensitivity of the flow tovarious disturbances remains. If disturbances to thelinearized governing eq...
Creator:
Kumar, Satish (University of Minnesota, Twin Cities)
Created:
2009-10-12
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
In this talk results of pressure gradient vs. volume flow rate calculations over a wide range of oscillatory frequencies for oscillatory tube flow of healthy human blood are performed using the non-homogeneous hemorheological model of Moyers-Gonzalez et al. [M.A. Moyers-Gonzalez, R.G. Owens, J. Fang, A non-homogeneous constitutive model for huma...
Creator:
Owens, Robert Gwyn (University of Montreal)
Created:
2009-09-17
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
Vesicles are locally-inextensible fluid membranes that cansustain bending. We consider the dynamics of flows ofvesicles suspended in Stokesian fluids. We use a boundaryintegral formulation for the fluid that results in a set ofnonlinear integro-differential equations for the vesicle dynamics.The motion of the vesicles is determined by balancingt...
Creator:
Zorin, Denis (New York University)
Created:
2010-08-03
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
Under the proper conditions, surfactant molecules can self-assemble intowormlike micelles, resembling slender rods, can entangle and impartviscoelasticity to the fluid. The behavior of wormlike micelles solutionsis similar to that of polymer solutions. The primary difference being that,unlike covalently bound polymers, micelles are continuously ...
Creator:
Rothstein, Jonathan P. (University of Massachusetts)
Created:
2009-10-13
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.
We discuss bacterial biofilms and the scope for describing their viscoelastic mechanical properties as a consequence of their underlying polymeric and multiphase morphology. Biofilms are the most prevalent phenotype of bacteria in nature. Biofilms form under conditions common in industry and in the body. They are structurally heterogeneous on mu...
Creator:
Solomon, Michael J. (University of Michigan)
Created:
2009-09-15
Contributed By:
University of Minnesota, Institute for Mathematics and its Applications.