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Solver Convergence Issue in 2D Brinkman Flow through Anisotropic Porous Medium (Wavy Channel)
Posted 13 ott 2025, 01:07 GMT-4 Computational Fluid Dynamics (CFD), Microfluidics, Porous Media Flow Version 6.0 1 Reply
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Hello,
I’m simulating steady-state flow in a 2D wavy channel using the Brinkman Equations interface (COMSOL Multiphysics 6.0). The flow domain is an anisotropic porous medium confined between two impermeable wavy walls.
MODEL SUMMARY: * consists of a wavy bottom that i defined using parametric curve * upper top plate is a moving plate with velocity lets say U0 in x direction and 0 in y * the left and right walls are not moving * No slip condition is applied for all * Physics used is brinkaman equation where the porous matrix is set to be a diagonal matrix where the diagonal entries were already defined in the parameters under global definitions. * Physics controlled mesh is used. * stationary study is added.
ERROR:
Failed to find a solution. Maximum number of Newton iterations reached. There was an error message from the linear solver. The relative residual (0.041) is greater than the relative tolerance. Returned solution is not converged. Not all parameter steps returned.
TRIED SO FAR: * Adjusted tolerances and damping * switched between direct solvers * increased iteration limits
QUESTIONS: * Recommended solver setup (Fully Coupled vs Segregated) for Brinkman flow? * Tips for stabilizing convergence in anisotropic, wavy porous domains? * Any scaling or nondimensionalization suggestions?
Any help to stabilize or improve convergence for this steady Brinkman model would be appreciated.
Regards!
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Hello Niloptal,
The boundary conditions result in an inconsistency at the top left and top right corners: per the side BCs, the horizontal velocity is zero, but per the top BC it is U0. My first instinct would be to apply at the top a velocity profile such that the velocity is U0 on most of the boundary but vanishes at its ends, and see if that solves the convergence issue. Also, have you set a reference pressure somewhere?
Best,
Jeff
-------------------Jeff Hiller
