k-Wave

1. m.schirru
   

   Member
   Joined: Apr '15
   Posts: 1

   Hello,

   I am new to k-wave and I am trying to simulate the propagation of an ultrasonic shear wave through a solid to a solid-liquid (viscoelastic) interface. The aim is to derive the shear stress and strain at the solid-liquid interface. The ultrasonic source should simulate a PZT crystal bonded on the top of the solid component so a time varying pressure source or a time varying particle velocity source would do the job. To solve the problem I am using the function pstdElastic2D just as reported in the paper "Modelling Elastic Wave Propagation Using the k-Wave MATLAB Toolbox", but I have the following doubts:
   -is it possible to model the fluid using some viscoelastic parameters (e.g. shear viscosity, shear modulus, shear penetration rate ecc) or the fluid is fully Newtonian (so no shear stress can propagate in the fluid)?
   -what would it be the best way to simulate a sinusoidal (n-cycles) excitation burst using pstdElastic2D?
   -Is there a better function to simulate shear harmonic plane wave propagation in viscoelastic media?

   Thank you for your help,

   Michele

   Posted 8 years ago #

2. Bradley Treeby
   

   Developer
   Joined: Mar '10
   Posts: 1,640

   Hi Michele,

   The material properties in the elastic code are specified in terms of the density, the shear and compressional sound speeds, and the shear and compressional absorption coefficients. If you know the shear viscosity and shear modulus in your fluid medium, you can calculate these parameters and include them in your simulation. In a heterogeneous medium, the material parameters are defined as matrices with the appropriate values assigned to each grid point (matrix element). There is no distinction between fluid and solid media in the code other than via the material parameters you define.

   There are several way to create a sinusoidal excitation. You could use the toneBurst function (although this always applies a Gaussian envelope, which may or may not be what you want - see this post for more details). Otherwise, you could just define a time varying sinusoid of the appropriate frequency and number of cycles, and then apply the desired envelope (or filter using filterTimeSeries).

   If you are only interested in steady state behaviour at a single frequency, you could try using a frequency domain finite element solver. There are lots of commercial and open source products available, although I don't have much experience with them.

   Hope that helps,

   Brad.

   Posted 8 years ago #

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