×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Start-up Poiseuille Flow

## Start-up Poiseuille Flow

(OP)
Hi,
I'm trying to solve start-up flow in a hollow cylinder with matlab and finite difference method. I'm still new in matlab and I have this code:

clear;clc;
h = 1;
Dr = 0.01; Dt = 0.01;
nmax = 4000; epsilon = 0.0001;
r  = [0:Dr:h];
t = [0:Dt:h];
beta=0.1;
n1 = fix(h/Dr)+1;
m1 = fix(h/Dt)+1;
% Initialize solution matrices
velocity = zeros(n1,m1)
velocityN =velocity
% Iterative process for the solution
for k = 1:nmax
% boundary conditions:
velocityN(:,n1)        = zeros(n1,1);

% Calculate psiN in interior points
for i = 2:n1-1
for j = 1:m1
velocityN(i,j+1)= (beta*(1-(1/(2*i)))*velocity(i-1,j)+(1-2*beta)*velocity(i,j)+beta*(1+1/(2*i))*velocity(i+1,j));
end;
end;
% Check convergence
nfail = 0;
for i = 1:n1
for j = 1:m1
if abs(velocityN(i,j)-velocity(i,j))>epsilon
nfail = nfail+1;
end;
end;
end;

if nfail > 0
velocity = velocityN;
else
return;
end;
end;
fprintf('No convergence after %i iterations.',k);
[X,Y] = meshgrid(r,t);
contour(X,Y,velocity',10)

however, for r=0 I have dv/dr=0 as the second boundary condition. How do I incorporate this into the program. dV/dr should be:
velocityN(0,j+1)=((1-4*beta)*velocity(0,j)+4*beta(velocity(1,j)))

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!