Steady or transient which is faster to get thermal steady status

hogglife · January 1, 2023, 12:02

Hi all,

I want to ask steady or transient which is faster to get thermal steady status.

My simulating object is a heater which is in a container. Gas flows through the container from an inlet and an outlet. The heating power of the heating unit in the heater is controled according to temperature of a point in the heater. The aim of adjusting heating power is to keep the temperature-monitored point in the heater around the target temperature. After the whole system, i.e. the heater and the flow around the heater, reaches thermal steady status, the uniformity of temperature distribution at the top surface of heater is to be checked.

I have shallow knowledge on CFD and know in steady analysis there is no accelerating item in the equation but do not know its effect on speed to reach steady status. My knowledge cannot answer steady or transient which is faster to get steady. Could anybody give explanation on this? Thank you very much!

Currently I have tried chtMultiRegionSimpleFoam. ChtMultiRegionFoam has not been tried.

Alczem · January 3, 2023, 04:24

If you only need a final state of your system, then a steady solver is usually the way to go, although you might want to look into pseudotransient solvers. They can be more stable depending on the kind of flow (buoyancy and natural convection for instance) and helped me quite a lot. But you should first try to use chtMultiRegionSimpleFoam for sure

January 1, 2023, 12:02	Steady or transient which is faster to get thermal steady status	#1
hogglife New Member Join Date: Sep 2022 Posts: 19 Rep Power: 4	Hi all, I want to ask steady or transient which is faster to get thermal steady status. My simulating object is a heater which is in a container. Gas flows through the container from an inlet and an outlet. The heating power of the heating unit in the heater is controled according to temperature of a point in the heater. The aim of adjusting heating power is to keep the temperature-monitored point in the heater around the target temperature. After the whole system, i.e. the heater and the flow around the heater, reaches thermal steady status, the uniformity of temperature distribution at the top surface of heater is to be checked. I have shallow knowledge on CFD and know in steady analysis there is no accelerating item in the equation but do not know its effect on speed to reach steady status. My knowledge cannot answer steady or transient which is faster to get steady. Could anybody give explanation on this? Thank you very much! Currently I have tried chtMultiRegionSimpleFoam. ChtMultiRegionFoam has not been tried.

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January 3, 2023, 04:24		#2
Alczem Senior Member Join Date: Dec 2021 Posts: 251 Rep Power: 6	If you only need a final state of your system, then a steady solver is usually the way to go, although you might want to look into pseudotransient solvers. They can be more stable depending on the kind of flow (buoyancy and natural convection for instance) and helped me quite a lot. But you should first try to use chtMultiRegionSimpleFoam for sure