Courant no. unstable

rishik686 · December 10, 2022, 06:03

Hi everyone,
I am trying to run a fluid flow simulation in an artery using pimple Foam.
But the courant number is increasing abruptly.

Earlier when i tried the same for simple tube it run perfectly with stable Courant No.

Please help me to stablize the courant no. so that my simulation can converge.

joshwilliams · December 19, 2022, 11:01

I guess the artery has some curvature near the outlets which causes backflow issues. You may wish to change your BCs to a robust one that cancels backflow (I think totalPressure and inletOutlet do this).

Difficult to help without info such as your BCs, y+, any turbulence model etc..

December 10, 2022, 06:03	Courant no. unstable	#1
rishik686 New Member Rishi Kumar Join Date: Jun 2022 Posts: 20 Rep Power: 3	Hi everyone, I am trying to run a fluid flow simulation in an artery using pimple Foam. But the courant number is increasing abruptly. Earlier when i tried the same for simple tube it run perfectly with stable Courant No. Please help me to stablize the courant no. so that my simulation can converge. __________________ Rishi K.

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December 19, 2022, 11:01		#2
joshwilliams Senior Member Josh Williams Join Date: Feb 2021 Location: Scotland Posts: 112 Rep Power: 5	I guess the artery has some curvature near the outlets which causes backflow issues. You may wish to change your BCs to a robust one that cancels backflow (I think totalPressure and inletOutlet do this). Difficult to help without info such as your BCs, y+, any turbulence model etc..