Non classé 2. Collapse

2. Collapse

This example simulates the collapse of a mass, which is initially square shaped. The plastic rheology has been chosen.
The artificial topography is defined with a mathematical function.

collapse

initial shape                                                                                                         final shape

Copy/paste these lines in the editor of Matlab. Save the .m-file, run VolcFlow and chose the file.

%A simple example to simulate a collapse in 2D
%basic instruction to write a VolcFlow file
nrow = 100;   %equations are in 2D. At least 3 lignes (or columns) should be defined, even for 1D simulation
ncol = 100; %number of column of the simulation
dx_horiz = 5;        %space step in x (in m)
dy_horiz = dx_horiz; %space step in y
dt=0.05;           %time step (in s)
tstep_adjust = 0;  %0 = the time step is fixed by the user, 1 = its varies in time using a CFL condition
dtplot = 1;        %time step for plot
tmax =  60;        %duration of the simulation
g=9.81;                  %gravity
cohesion = 5000;         %cohesion or yield strength (depending of the rheology used)
rho = 2000;              %density (kg/m3)
representation = ‘surf(x,y,z+h,h); axis equal;pause(0.1);colormap(mycol);‘; %function used for the visualisation of results (at each dtplot)
f_avi = ”;  %avi file done with the plots. ” = no movie is done
f_data = ”; %save various variables at each dtplot. ” = no data is saved
bound_cond = ”;
%vectors x and y – not needed by VolcFlow (for the visualisation of results only)
x = [dx_horiz/2:dx_horiz:ncol*dx_horiz-dx_horiz/2];
y = [dy_horiz/2:dy_horiz:nrow*dy_horiz-dy_horiz/2];
%definition of the topography
z = 50*sin(y’/100)*sin(x/50);
%definition of the initial thickness
h=z*0;
h(70:80, 40:50)=10; %initially the mass that will flow is a square
%initial velocity – 0 here
u_xx = z(1:nrow, 1:ncol-1)*0;
u_xy = z(1:nrow, 1:ncol-1)*0;
u_yy = z(1:nrow-1, 1:ncol)*0;
u_yx = z(1:nrow-1, 1:ncol)*0;
mycol = jet; %used to modify the colormap
mycol(1,:)=[1 1 1];
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