k-Wave

1. anil
   

   Member
   Joined: Mar '16
   Posts: 15

   Hi Bradley,

   I have a couple questions about elastic and thermal diffusion simulation. I use pstdElastic2D function for bone simulation. In a paper, you mentioned that square of velocities proportional to heating. In addition, you recently released a new thermal diffusion function. So, my questions are:

   1- Is it possible to use a heterogeneous medium in Thermal Diffusion code? (I looked the example but I couldn't find.)

   2- Is it possible to examine dispersion in pstdElastic2D? If it is possible how should I arrange my source and sensor positions? or Would you suggest any documents about the issue?

   3- I saw some of your reply on the form that you recommend convergence. How can I use that method, do you have any suggestion about it?

   Best,
   Prof. AK

   Posted 5 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi Prof. AK,

   (1) Yes, just define medium.thermal_conductivity (etc) as matrices the same size as the computational grid instead of single values.

   (2) Do you mean dispersion as in extracting dispersion curves (related to wave modes), or dispersion as in numerical dispersion?

   (3) The basic idea is to take your simulation, increase Nx, Ny, Nz by a factor and decrease dx, dy, dx by the same factor (so the physical dimensions of the simulation stay the same) and compare the results. Keep doing this until the results don't change anymore.

   Brad.

   Posted 5 years ago #

3. anil
   

   Member
   Joined: Mar '16
   Posts: 15

   Hi Bradley,

   Thank you so much for your detailed explanation.
   In the second question, I was asking for both extracting and numerical dispersion.

   Best,
   Prof. AK

   Posted 5 years ago #

4. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,643

   Hi Prof. AK,

   To avoid numerical dispersion, perform a convergence test in time (i.e., run the simulation with a smaller dt and larger Nt but the same physical time and check the answer is the same).

   For dispersion curves, a good place to start is "Ultrasonic Guided Waves in Solid Media" by Joseph Rose.

   Brad

   Posted 5 years ago #

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