k-Wave

1. AndresMM
   

   Member
   Joined: Feb '16
   Posts: 4

   Hi everyone,

   I am trying to model the acoustophoretic effect of ultrasound excitation on a column of water containing a particle bed with sizes in the range of 20-90 micrometers. To do this I want to find the pressure and speed time-averaged effects (P_rms and U_rms) and calculate the Gorkov potential, its gradient and obtain the acoustic radiation forces field. My idea is to afterwards couple this force field to an external CFD simulation and see how different sized particles will behave under different flow conditions. Something similar has already been done for microfluidic setups (http://pubs.rsc.org/en/content/articlelanding/2012/lc/c2lc40733g#!divAbstract) or (http://pubs.rsc.org/en/content/articlelanding/2015/lc/c5lc00866b#!divAbstract) (However they used a FEM simulation, COMSOL multi-physics).

   I want to use kwave for the steps of finding P_rms and U_rms for my geometry. However I have some doubts regarding the modeling of the particle bed. What I have done so far is create a porous bed on the bottom of the column. My 2D-mask looks like this http://imgur.com/a/vpy1B , where the transducer is the top small line and is in direct contact with the main medium (water), the vertical lines are the tank walls (PMMA), and the bottom is a steel bottom (which acts as a wave reflector).

   - How well can KWave manage such a "complex" geometry including holes and porosities?
   - Am I right in believing that an elastic simulation is strictly necessary to find the resulting P_rms and U_rms of the geometry?
   - Would you have any advice regarding the problem in general?

   Cheers,
   Andrés

   Posted 8 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi Andres,

   The main challenge with any grid based method (including k-Wave) is the accuracy with which you represent the heterogeneous structure of the material on the discrete grid. In some cases, the actual structure isn't that important, just the statistical effect it has on the propagating wave field. k-Wave doesn't have a problem with this type of geometry per-se, but you might want to perform a convergence study. That is, check to what degree the simulation output depends on the grid discretisation. If you want another model to compare to, you could also try SimSonic. I've got a wrapper function that lets you call SimSonic2D with k-Wave inputs if that is helpful.

   Regarding elastic vs fluid simulation, I don't have much experience with the situation you are interested in, but if the media can support shear, then an elastic simulation is probably necessary. In any case, it should be easy enough to run the simulation with the k-Wave fluid and elastic codes and compare the results.

   Hope that helps,

   Brad

   Posted 8 years ago #

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