Unsteady Flow Initial Conditions

recon9 · March 16, 2011, 15:40

I am curious as to what the initial conditions within the setup initialization refers to. I have a domain with fluid flowing in at 29m/s in +U direction. If I set the initial condition to 29m/s does that mean the fluid entering the domain is traveling at that speed or does it mean the domain is traveling at that speed?

I want the domain to remain stationary, that is why I ask. I have been entering 0 for U, V, W and it takes a while for the solution to converge but it also looks like the solution is starting with the fluid flow at 0 then speeding up to 29.

Thanks for your insight.

Brady

Josh · March 16, 2011, 19:37

Initialization refers to the entire domain. So if your initial velocity is 29 m/s, the entire domain will experience this simultaneously. It your initial velocity is 0 and the inlet velocity is 29 m/s, the simulation will take longer since the flow will have to first travel from the inlet to your region of interest.

March 16, 2011, 15:40	Unsteady Flow Initial Conditions	#1
recon9 New Member Brady Join Date: Jan 2011 Location: Calgary, Alberta, Canada Posts: 12 Rep Power: 15	I am curious as to what the initial conditions within the setup initialization refers to. I have a domain with fluid flowing in at 29m/s in +U direction. If I set the initial condition to 29m/s does that mean the fluid entering the domain is traveling at that speed or does it mean the domain is traveling at that speed? I want the domain to remain stationary, that is why I ask. I have been entering 0 for U, V, W and it takes a while for the solution to converge but it also looks like the solution is starting with the fluid flow at 0 then speeding up to 29. Thanks for your insight. Brady

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March 16, 2011, 19:37		#2
Josh Senior Member Joshua Counsil Join Date: Jul 2009 Location: Halifax, Nova Scotia, Canada Posts: 366 Rep Power: 18	Initialization refers to the entire domain. So if your initial velocity is 29 m/s, the entire domain will experience this simultaneously. It your initial velocity is 0 and the inlet velocity is 29 m/s, the simulation will take longer since the flow will have to first travel from the inlet to your region of interest.