title	date	author	mathjax
CFS-PML2nd Manual	2020-10	Yufeng Wang	true

Overview of CFS-PML2nd package

CFS-PML2nd is a C-based code package that implements unsplit CFS-PML for fractional viscoacoustic simulation. This package is provided for verifying the feasibility and stability of the proposed CFS-PML when used to the second-order rather than first-order wave equation. We provide two package versions: cfspml2nd for viscoacoustic modeling with CFS-PML; pml2nd for viscoacoustic modeling with standard PML. The package has been well test on Linux OS (Ubuntu 18.04 TLS) with g++ and SeismicUnix (https://github.com/JohnWStockwellJr/SeisUnix) available.

The architecture of CFS-PML2nd package

• input: accurate velocity and $Q$ model for $Q$-RTM:
  • acc_vp.dat: quasi-Marmousi velocity model;
  • acc_Qp.dat: quasi-Marmousi $Q$ model;
• output: generated results include:(seismograms, snapshots, and energydecay).
  • visco_1_1_profile.dat: seismograms recorded at the surface;
  • energydecay.dat: energy decay of the computational domain;
  • visco_1_1_receive(1-4).dat: seismic records at four receivers;
  • visco_1_1_snapshots1_(0-8000).dat: snapshots recorded at every 100 time steps;
• plot: scripts for plotting figures, which includes:
  • energydeacy.m: plot the energy decay of the CFS-PML and standard PML schemes;
  • snapscpml.m: plot the snapshots of the CFS-PML scheme at some time slices;
  • snapspml.m: plot the snapshots of the standard PML scheme at some time slices.
• Myfunctions.h: header file;
• Myfunctions.c: subfuncations file;
• viscocpml.c: C code file, there are serveal important parameters to control performance of CFS-PML2nd, which includes:
  • nt: the time steps for simulation, if you want to have a quick test, set nt=2000 or less,

	int nt=8000;

- `Memory_len` you can set `Memory_len=40` for quick test, and `Memory_len=300` or more for removing the side effects of this approximation.

int Memory_len=300;	//>=4

- `Gmax` and `Amax`: these parameters are defined for CFS-PML, one can change them for test. If `Gmax = 1.0` and `Amax = 1.0*pi*f0`, the SFS-PML reduces to standard PML scheme.

	float R=1E-6;
	float Vmax=3000.0;
	float Gmax=1.0;
	float Amax=1.0*pi*f0;

-Makefile: excution script.

Prerequisites

CFS-PML2nd package is developed under Linux system, which should be equipped with the following environments:

• C environment (gcc or g++);
• SeismicUnix;
• Matlab;

How to run this package

• Step 1: Confirm the environment in Makefile, and replace the folder path with your own enviroment path;

INC1=/home/wyf/SeismicUnix/include
INC2=/home/wyf/SeismicUnix/src/Complex/include
LIK1=/home/wyf/SeismicUnix/lib
LIK2=/home/wyf/SeismicUnix/src/Complex/lib
LIB=-lsu -lpar -lcwp -lm

all: viscocpml.c
	g++ -o a.out viscocpml.c -fopenmp -I$(INC1) -I$(INC2) -L$(LIK1) -L$(LIK2)  $(LIB)
	clear        
	nohup ./a.out&

• Step 2: Run the Makefile by the command line: make;
• Step 3: View generated files in the folder ./ouput;
• Step 4: Plot figures by run /plot/energydeacy.m, /plot/snapscpml.m, /plot/snapspml.m.

Contact me

I am Yufeng Wang, an associate researcher from China University of Geosciences, Wuhan. If you have any question about this coda package, please feel free to contact me by Email:wangyufeng@cug.edu.cn.

Copyright

CFS-PML2nd is a C-based code package that implements unsplit CFS-PML scheme for fractional viscoacoustic simulation.

The Marmousi model used in this package is available for download from Madagascar MainPage http://www.ahay.org/data/marm2

Copyright (C) 2020 China University of Geosciences, Wuhan (Yufeng Wang)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.