Laminar Pipe Flow Simulation/Help Please
I simulated 2D Laminar pipe flow, and used periodic boundary conditions at outlet and inlet of pipe. I tied two method respectively to define the periodic boundary conditions: pressure gradient and mass flow rate(per 2*Pi). However, all the simulation results didn't agree with the analytical resutls. I cannot figure out the reasons.
Any suggetions would be preferred. Thanks. 
Re: Laminar Pipe Flow Simulation/Help Please
1.You are using the axissymmetric model..? if you are,just specify one side of your 2D geometry as axis. and pay attention to specify the correct pressure gradient at periodic boundary according to the laminar theory.. 2.Maybe you can try another method,i.e,writting a velocity inlet UDF and using velocity inlet and pressure oullet instead of periodic boundary... 3.By the way ,are you doing 3D circular tube numerical simulation..? and you just simplified it into a 2D axissymetric model?

Re: Laminar Pipe Flow Simulation/Help Please
Hi, Majestyezh. Thanks for your kind help.
I am trying to simulate 2D fully developed laminar pipe flow as the first step of my research. As you suggested I specified the centerline of tube as axis(X axis) and used steady axisymmetric model(the reason I adoped steady model, I thought, was that the pipe length could be not necessarily long enough to obtain fully develped flow). The B.C of my future research topic is periodic, therefore, in this 2Dfullydevelopedlaminarpipe flow simulation, I used translationally periodic B.C.. I input pressure gradient(small enough to gurantte laminar flow)for this periodic B.C., and I surely got probolic velocity profile of laminar flow, however, the scale of velocity is smaller than that of it should be(I compared the simulation result with analytical result). I also tried Mass Flowrate input,and got similar problem. While, I tried Velocity profile inlet and outflow outlet(maybe I could later try pressure outlet as your suggestion 2), simulation results agree with analytical results. So, I cannot figure out why Periodic B.C with steady model doesn't work for the case of 2DF.D.LaminarPipe flow? 
Re: Laminar Pipe Flow Simulation/Help Please
I figured out the question: not enough nodes on calculation domain.

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