Dear Comsol gurus,
I have been dealing with a CFD/transport of diluted species (TDS) simulation for a while and I was hoping you could bring some light to the subject.
I am simulating a flow in a micro mixer (related to example: www.comsol.com/showroom/gallery/320/) using laminar flow and transport of diluted species. I want to emulate the behaviour of the so called "chaotic mixers" in which a laminar flow with an initial concentration of a specie "c" is "streched and bent" in order to mix "c" in the entire volume. The chaotic mixer is used in small channels (µm and mm) due to the lack of turbulent forces.
I am not having any results so far. I have uploaded the convergence plots for both step 1: laminar flow, step 2: TDS and my model. At the beginning I wanted to define a lateral (zx in this case) boundary as symmetric boundary for then mirror it. The latter was unsuccessful and I defined it as a wall without results. I have used the default iterative solver and direct solver, I have change the mesh from coarser to fine, I also changed the multigrid mesh coarsening factor from 2 to 1.5 and increase the relative tolerance, all of them at the same time or each one separatelly without any success.
My first guess is that the large "turbulence" made by the bending and streching of the flow might increase each time the error in each iteration leading to a never ending iterative process. But the people involved in the original article was successful in their simulation using periodic boundary conditions but I dont know how to use them.
Sorry for the long post but I wanted to give you a better picture of my situation. Your ideas are more than welcome
My best regards
Miguel
I have been dealing with a CFD/transport of diluted species (TDS) simulation for a while and I was hoping you could bring some light to the subject.
I am simulating a flow in a micro mixer (related to example: www.comsol.com/showroom/gallery/320/) using laminar flow and transport of diluted species. I want to emulate the behaviour of the so called "chaotic mixers" in which a laminar flow with an initial concentration of a specie "c" is "streched and bent" in order to mix "c" in the entire volume. The chaotic mixer is used in small channels (µm and mm) due to the lack of turbulent forces.
I am not having any results so far. I have uploaded the convergence plots for both step 1: laminar flow, step 2: TDS and my model. At the beginning I wanted to define a lateral (zx in this case) boundary as symmetric boundary for then mirror it. The latter was unsuccessful and I defined it as a wall without results. I have used the default iterative solver and direct solver, I have change the mesh from coarser to fine, I also changed the multigrid mesh coarsening factor from 2 to 1.5 and increase the relative tolerance, all of them at the same time or each one separatelly without any success.
My first guess is that the large "turbulence" made by the bending and streching of the flow might increase each time the error in each iteration leading to a never ending iterative process. But the people involved in the original article was successful in their simulation using periodic boundary conditions but I dont know how to use them.
Sorry for the long post but I wanted to give you a better picture of my situation. Your ideas are more than welcome
My best regards
Miguel