专门用于计算频散现象的matlab程序，各种功能函数都提供，并且还有举例说明，希望对大家的研究有所帮助.zip

% Purpose: % Help function: explanation how to run the code for the two examples described in the paper: % % F. Karpfinger, H.-P. Valero, B. Gurevich, A. Bakulin, B. Sinha, 2010, % Spectral-method algorithm for modeling dispersion of acoustic modes in elastic % cylindrical structures % Geophysics, 75, H19-H27. % doi: 10.1190/1.3380590 % % Author: Florian Karpfinger 01/09 % % Most of this package is % Copyright (c) 2010 by the Society of Exploration Geophysicists. % For more information, go to http://software.seg.org/2010/0003 . % You must read and accept usage terms at: % http://software.seg.org/disclaimer.txt before use. % % % The routine "chebdif.m" was written by J. A. C. Weideman and is public domain. % However, the author requests that he be referenced when his code is reused. % Do not remove the references to the author from chebdif.m. % %In order to run the spectral method code for computing dispersion and %radial profiles in cylindrical elastic-fluid structures three files need to be %possibly manipulated by the user % 1. ComputeDispersion.m % 2. ReadInput_xx.m % 3. PlotDispersion.m %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % In order to run the Example 1 attached follow the following steps: % => open the three files mentioned above (for example 1: DefineModelParams_1.m) %% 1. ComputeDispersion.m % => make sure that in ComputeDispersion.m in line 23 there is written: % for example 1: [Par] = DefineModelParams_1; or % for example 2: [Par] = DefineModelParams_2; % => this is the file which needs to be run %% 2. ReadInput_1.m % The file has the following form: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % %Two layer model % % Par.N=[20,60]; %Number of Chebychev points; must be the same number of points for radial profiles % % Par.vpf=[1500,4878]; %P-wave velocities in [m/s] % % Par.vs=[0,2601]; %S-wave velocity in [m/s] % % Par.rho=[1000,2160]; %Densities in [kg/m^3] % % Par.A=[1e-4,0.1,1.5]; %Radii in [m] % % %radii of each layer in [m] (the first value corresponds % % %to the center which can not be set equal to zero due to the singularity in cylindrical % % %coordinates: 1/r) % % % % % % Par.SelectminVel = 0; %smallest displayed velocity in [m/s] % % Par.SelectmaxVel = 5000; %highest displayed velocity in [m/s] % % % % %Surface boundary conditions % % Par.s=1; %0= stress free boundary conditions on the surface % % %1= rigid boundary condititions on surface % % Par.comp =1; %1= dispersion for a whole frequency intervall is computed % % %2= radial profiles (distribution of displacement and stress along the radius of the structure) % % % % % % if Par.comp == 1 % % Par.wmin=200*2*pi; Par.wstep=200*2*pi; Par.wmax=10010*2*pi; % %Frequency Range for dispersion % % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % elseif Par.comp == 2 % % Par.w= 1500*2*pi; % single frequency for radial profiles % % % % Par.wstep = Par.w; % % Par.wmin = Par.w; % % Par.wmax = Par.w; % % end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % => line 46-51 define the elastic and geometric parameters for each layer (from the center of the structure to the outside of the structure) % => for computing the dispersion the number of Chebychev points can be % different for each layer (depending on the thickness of the layer) % => for computing radial profiles the number of points have to be the same %% 3. PlotDispersion % => the only thing to be possibly changed here is either their axis ranges, % color or line style % => for the radial profiles the modes to be plotted can be changed withmode_num % %% Run Example 1 %%%%%%%%%%%% %DISPERSION% %%%%%%%%%%%% % => first compute the dispersion % make sure that in ReadInput.m you have: % Par.SelectminVel = 0; %smallest displayed velocity in [m/s] % Par.SelectmaxVel = 5000; %highest displayed velocity in [m/s] % => this makes sure that all eigenvalues computed are displayed % Par.Comp = 1; (ReadInput.m) % after computing this it will be obvious that there are spurious % eigenvalues for low velocities which are not of interest (set=>Par.SelectminVel according to that) % for the higher order modes the same can be done depending on which modes % are of interest % for example 1: if only the tube wave is of interest choose % Par.SelectminVel = 1000; %smallest displayed velocity in [m/s] % Par.SelectmaxVel = 2000; %highest displayed velocity in [m/s] % => compute dispersion again (run: ComputeDispersion.m) (now only the tube wave will be displayed) %%%%%%%%%%%%%%%%% %RADIAL PROFILES% %%%%%%%%%%%%%%%%% %now compute the radial profiles for the tube wave %change Par.Comp = 2; (ReadInput.m) % choose a frequency to compute the radial profiles for (Example 1: 1500 Hz) % => compute radial profiles (run: ComputeDispersion.m) %% Exmple 2 % same workflow but the range of velocities of interest are different