kWaveModel_coarse_2D_withAbsorption_newTimestep.m

%% ========================================================================
% PRELIMINARY STEPS
% Clear variables
clear
clc

%% ------------------------------------------------------------------------
% DEFINITION OF INPUT DATA
% Definition of grid properties
x=58e-3;                            %[m] Width of the sample
y=18e-3;                            %[m] Height of the sample
z=18e-3;                            %[m] Depth of the sample
dx = 0.075e-3;                      %[m] grid point spacing in the x direction
dy = dx;                            %[m] grid point spacing in the y direction
dz = dx;                            %[m] grid point spacing in the z direction
CFL = 0.1;                          % CFL number

% Conversions of values to grid points
x = ceil(x/dx);                     % [grid point] Width of the sample
y = ceil(y/dy);                     % [grid point] Height of the sample
z = ceil(z/dz);                     % [grid point] Depth of the sample
PML_size=20;                        % [grid points] Area required for the PML

% Optimize Nx,Ny,Nz values to low prime numbers (file contains all numbers,
% that contain low prime factors)
load prime_numbers.mat
    
% Definition of computational grid
Nx = prime_num(find(prime_num>=x+2*PML_size,1));   % Number of grid points in the x (row) direction
Ny = prime_num(find(prime_num>=y+2*PML_size,1));   % Number of grid points in the x (row) direction
Nz = prime_num(find(prime_num>=z+2*PML_size,1));   % Number of grid points in the x (row) direction
% Recalculate x,y,z
x = Nx-2*PML_size;
y = Ny-2*PML_size;
z = Nz-2*PML_size;

kgrid = makeGrid(Nx, dx, Ny, dy);

%% Medium Properties - Part 1
% Materials
% Acoustic properties of water (at 50C)
sound_speed = 1543;         % [m/s] Sound speed of the medium
density = 988;             % [kg/m^3]
alpha_coef_water = 0.0022;      %[dB/(MHz^b*cm)] Power law absorption prefactor (a)
b_water = 2;             %Power law absorption exponent (b)
% Acoustic properties of Material 1
sound_speed_1 = 1770;      % [m/s] Sound speed of the medium
density_1 = 894;           % [kg/m^3]
alpha_coef_1 = 4;        %[dB/(MHz^b*cm)] Power law absorption prefactor (a)
b_1 = 1.18;                 %Power law absorption exponent (b)
% Acoustic properties of Material 2
sound_speed_2 = 1680;        % [m/s] Sound speed of the medium
density_2 = 1109;            % [kg/m^3]
alpha_coef_2 = 8.4;          %[dB/(MHz^b*cm)] Power law absorption prefactor (a)
b_2 = 0.99;                    %Power law absorption exponent (b)
% Acoustic properties of Copper
sound_speed_3 = 4660;          % [m/s] Sound speed of the medium
density_3 = 8900;              % [kg/m^3]
alpha_coef_3 = 0.01;         %[dB/(MHz^b*cm)] Power law absorption prefactor (a)
b_3 = 2;                    %Power law absorption exponent (b)



%% Grid details
% Definition of sample
dia_out = 84e-3;                %[mm]Outer diameter of the sample
dia_out = floor(dia_out/dx);    %[grid point]Outer diameter of the sample
M1_out = 1.7e-3;                %[mm]Thickness of outer layer
M1_out = floor(M1_out/dx);      %[grid point]Thickness of outer layer
M1_in = 44.6e-3;                %[mm]Diameter of inner area