(Biomedical Engin.) Fluid flow through a semi-porous membrane (COMSOL)

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SUMMARY

The discussion revolves around modeling fluid flow through a semi-porous membrane using COMSOL Multiphysics. The user seeks guidance on establishing boundary conditions (BCs) for a system that removes waste water at a rate of approximately 1 mL/min, with an inlet pressure of 80 mm Hg and an outlet pressure of 40 mm Hg. Key considerations include the choice of membrane thickness, porosity, and the implementation of a partition coefficient for flux concentration differences. The user also inquires about the potential use of incompressible Navier-Stokes equations and Brinkman's Equations for improved modeling accuracy.

PREREQUISITES
  • Familiarity with COMSOL Multiphysics, specifically convection and diffusion modeling.
  • Understanding of boundary conditions in fluid dynamics.
  • Knowledge of partition coefficients and their application in mass transfer problems.
  • Basic principles of incompressible Navier-Stokes equations and Brinkman's Equations.
NEXT STEPS
  • Research how to implement boundary conditions in COMSOL for fluid flow problems.
  • Explore the use of partition coefficients in COMSOL for modeling concentration gradients.
  • Study the application of incompressible Navier-Stokes equations in COMSOL for complex fluid dynamics.
  • Investigate the effects of membrane thickness and porosity on fluid flow and waste removal efficiency.
USEFUL FOR

Biomedical engineers, fluid dynamics researchers, and anyone involved in modeling membrane processes using COMSOL Multiphysics.

juvel006
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Hi all -

I have a problem that I'm probably going to model in COMSOL and would love to hear some ideas on how to get the proper BCs.

Attached is the picture from Truskey. Essentially, the problem consists of removing waste (water) from the membrane tube at a rate of ~ 1 mL/min with a pressure driven flow ~ 80 mm Hg inlet and ~ 40 mm Hg at the outlet. The radius of the tube should be around ~ 8-10 mm, and length, thickness, and porosity of the membrane to be chosen for optimal and desired waste removal.

I'm using COMSOL's convection and diffusion modeling. The inlet is a known concentration of waste and velocity profile. The outlet BC I use is convective flux resultant from flow out of the pores. The membrane BC is where I'm not sure what to use. Right now, It's a partition coefficient problem with a flux concentration difference (something like K*(C_inside-C_outside)).

I haven't gone into the full problem really, but I was just wanted some feedback on how to set up my BCs properly to capture the waste removal at the membrane of ~ 1ml/min... Another attached picture is the actual modeling domain used. So basically, how can I capture the removal of ~ 1ml/min of waste (water) from the permeate side in COMSOL? Is there a better way to set this problem up using incompressible Navier Stokes in COMSOL to use Brinkman's Equations for the membrane part? If so, how would I go about it given the general problem I've described as far as BC implementation.

Thanks for any feedback.
 

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juvel006 I am working on a very similar problem and was curious how you went about solving yours in the end? Thanks.
 
ACulberson said:
juvel006 I am working on a very similar problem and was curious how you went about solving yours in the end? Thanks.
Welcome to the PF. :smile:

From the Profile page for @juve006, his last sign-on was in 2010. So he may not answer your question anytime soon. Go ahead and start your own thread with your question, and post as much work as you can so we can see where you are. Thanks.
 

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