Darcy's law

clc
clear
% Laplace equation
% Define the length of the grid
L  = 5 ;
% Define the Width of the grid
B = 5 ;
nx = 4 ;
ny = 4 ;
dx = 100;
dy =  100;
h=zeros(nx,ny);
amax = 0;
% boundry conditions
h(1,:)  = [ 8.04 , 7.68 , 7.19 , 6.82 ];
h(nx,:) = [ 8.53 , 8.41 , 8.33 , 8.29 ];
h(:,1)  = [ 8.04 , 8.18 , 8.36 , 8.53 ];
h(:,ny) = [ 6.82 , 7.56 , 7.99 , 8.29 ];
while amax <= 0.01
	for j = 2 : nx-1
		for i = 2 : ny-1
			oldval = h(i,j);
			h(i,j) = ( h(i-1,j) + h(i+1,j) + h(i,j-1) + h(i,j+1)/4) ;
			e = abs(h(i,j)) - oldval;
			if e > amax
				amax = e;
			end
		end
	end
end
h

I NEED TO GET TO THE FOLLOWING RESULT

8.04 8.18 8.36 8.53

7.68 7.93 8.19 8.41

7.19 7.68 8.05 8.33

6.82 7.56 7.99 8.29

Can you suggest for me the correction and thank you :)

[darova]

[hasan damaj]

im dividing the value of h(i,j-1)/4 whats wrong?

[darova]

Aha, ok

[hasan damaj]

sir,

i need to get to the specified answer plz..

i have a problem if u can just give me advice

thank you

[darova]

Did you try to divide all elements? NOt only last one

h(i,j) = ( h(i-1,j) + h(i+1,j) + h(i,j-1) + h(i,j+1))/4 ;

[hasan damaj]

the equation is correct sir..

[hasan damaj]

the while condition is not working with me

Answer 1

[Image Analyst]

You're setting up your boundary conditions incorrectly. You're overwriting the corners with different numbers. I think maybe you want this:

% Initialize boundary conditions:
h(1,:)  = [ 8.04 , 7.68 , 7.19 , 8.53];
h(end,:) = [6.82 , 7.56 , 7.99 , 8.29 ];
h(2:3,1)  = [7.68;7.19];
h(2:3,end)  = [8.41; 8.33];
h
% Here h should be
% 8.04          8.18    8.36    8.53
% 7.68           0       0      8.41
% 7.19           0       0      8.33
% 6.82          7.56    7.99    8.29

Adapt as needed.

[hasan damaj]

but the i need to replace the 0 by the values of the h(i,j) equation..

[Image Analyst]

What is your input matrix supposed to look like? From your code it looks like you were attempting to set only the outer edges of the matrix. And then your code would do something to set the interior of the matrix (I didn't delve into the algorithm you used for the loop).

[hasan damaj]

im setting the outer edges..i need from the while loop to run throught the equation for differenet vallues of i and j in the euqation h(i,j) ..

attached is the original code form different program

[Image Analyst]

It looks like the first index for H is the column, and second is the row - the opposite as MATLAB. Is that how you understand it?

[hasan damaj]

correct sir i know about this :)

[hasan damaj]

but the values of inner index are zeros after running the code..

[hasan damaj]

how do i edit it to reach my results and thank you

Answer 2

[Hassan Abdullah Saleem]

I think I know what is the probelm in your code..you have overlap intry try to inter the boundary by value like this h(1,1) = 8.04

Answer 3

[Hassan Abdullah Saleem]