2D diffusion equation for a laser heat source
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I am writing a code for laser source. However, when I am incorporating the source term, I am getting an error saying mismatch of array dimensions. I also want a plot between temperature and time. How to do that? Is there any issue with the CFL condition?
clc;
clear all;
% Parameters
rho=2600;
cp=473;
% domain and step
Lx=10;
Ly=10;
Nx=51;
Nt=3000;
Ny=51;
dx=Lx/(Nx-1);
dy=Ly/(Ny-1);
%CFL condition
c=1;
C=0.05;
dt=(C*dx/c);
%field variables
Tn=zeros(Ny,Nx);
x=linspace(0,Lx,Nx);
y=linspace(0,Ly,Ny);
[X,Y]=meshgrid(x,y);
q_dot=2.36*10^14*exp(-(800)*((x).^2+(y).^2));
K=ones(Ny,Nx);
K(1:Lx,1:Ly)=0.078;
%Initial condition
Tn(:,:)=0;
t=0;
%Loop
for n=1:Nt
Tc=Tn;
t=t+dt;
for i=2:Nx-1
for j=2:Ny-1
Tn(j,i)=Tc(j,i)+ ...
dt* (K(j,i)/rho/cp)*...
((Tc(j,i+1)+Tc(j+1,i)-4*Tc(j,i)+Tc(j-1,i)+Tc(j,i-1))/dx/dx);
end
end
%Source term
Sx=round(5.1*Nx/Lx);
Sy=round(9.9*Ny/Ly);
if (t<3)
Tn(Sy,Sx)=Tn(Sy,Sx)+dt*q_dot/rho/cp;
end
%Boundary condition
Tn(1,:)=0;
Tn(end,:)=0;
Tn(:,1)=0;
Tn(:,end)=Tn(:,end-1);
%Visualize
mesh(X,Y,Tn);
axis([0 Lx 0 Ly 0 50]);
title(sprintf('Time=%f seconds',t))
pause(0.1);
end
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回答(1 个)
Torsten
2023-8-13
编辑:Torsten
2023-8-13
qdot is 1x51, T(Sy,Sx) is a scalar. Thus
Tn(Sy,Sx)=Tn(Sy,Sx)+dt*q_dot/rho/cp;
tries to assign an array to a scalar which throws an error.
And why do you mix lengths and number of elements and switch between x and y in the definition of K ?
K=ones(Ny,Nx);
K(1:Lx,1:Ly)=0.078;
2 个评论
Torsten
2023-8-13
编辑:Torsten
2023-8-13
In what region of your domain do you want to set the source term ? And how should the source term look like in this subdomain ?
"qdot" in your code is a vector of size 1x51, and you are lucky that Nx = Ny, otherwise MATLAB would have thrown an error when you compute "qdot" as
q_dot=2.36*10^14*exp(-(800)*((x).^2+(y).^2));
It is not obvious how "qdot" of size 1x51 is related to the domain which has a 51x51 grid.
Maybe you want
q_dot=2.36*10^14*exp(-(800)*((X).^2+(Y).^2));
I don't know.
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