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 Goutam March 19, 2012 14:44

problem on Laminar flow in a pipe

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Since I have consider the same velocity (measured from the formula
Vc { 1 - (r/R)^2 } at the inlet and outlet Bcs, I am expecting a linear profile for velocity magnitude but I am getting a parabolic profile? Is this correct? Problem description is given below.

Fully developed Laminar flow in a pipe: (Solver: simpleFoam)

L = 1.2 m, R = 0.0295 m, D = 2R = 0.0519 m,
Re = 100, neu = 1.004 E -6 m^2/s.

Entrance length, Le = 0.3114 m, Avg Velocity, Vc = 0.001934 m/s.
At r = 0, Vmax = 2*Vc = 0.0038682 m/s.

Initial Condition: velocity = (0 0 0), Bcs: Inlet and outlet velocity, V = Vmax and wall velocity = (0 0 0).
Initial Condition for p = 0, Boundary condition for p: Inlet and Wall: Pressure gradient is zero, outlet : p = 0.

Thanks

 kmooney March 19, 2012 18:58

The steady state velocity profile for a laminar flow in a pipe is parabolic. Unless I'm confused it looks as though you are in fact getting the correct solution.

 Goutam March 20, 2012 06:13

Since, I have used parabolic velocity at the both ends (inlet and outlet) then the velocity profile should be a linear profile. Am I right?

 kmooney March 20, 2012 10:37

Quote:
 Originally Posted by Goutam (Post 350381) Since, I have used parabolic velocity at the both ends (inlet and outlet) then the velocity profile should be a linear profile. Am I right?
What do you mean by "linear profile"? The pressure should decrease linearly from inlet to outlet if that's what you mean. Due to continuity, however, the velocity profile will not change.

 Goutam March 20, 2012 11:13

Sorry, I got the error. my result was correct but I want to use parabolic BC but I have used uniform BC. I want to use U(x) = 2U_0 [ 1- (x/r)^2 ]. This is the problem.

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