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fruitkiwi May 14, 2012 01:04

initial condition setting in transient from steady?
Today come across this question,it surprise me.

I recall in fluent i once draw a pipe, which has constant velocity at the inlet as 0.1m/s, and has outlet pressure set as 0, run in steady state.

then i use it as initial condition in the transient state. which has a velocity profile start with velocity 0m/s at t=0, pressure set as 0, run in transient state.

I thought is good.But not, why i need specify the velocity 0m/s at t=0, should'nt it be replaced by the steady state solution, i should set it as 0.1m/s at t=0 to make it converge easily?

am i wrong?

fruitkiwi May 15, 2012 08:57

I think i do not make myself clear and there's why not reply.

My problem is to use steady solution as initial condition for a transient problem, the first time point on the velocity profile in transient must match with the velocity profile at the steady solution, so it do not create a "discontinuity" in the solver setting, to bypass the convergence issues

example: velocity is 0.01m/s in steady, then my transient velocity profile, t=0, must be 0.01m/s or can i specify it as 0?

i am struggling to find some book to prove it, is there any one agree with me?

i know it sounds silly. :)

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