Learning Forum

[Sravan B]

Hello,

I am simulating a battery pack cooled by PCM (Phase Change Material) and liquid cooling. I aim to implement a delayed boundary condition where the velocity inlet boundary condition is activated only when the PCM liquid fraction reaches 0.6. For the liquid cooling setup, I have applied velocity inlet and pressure outlet boundary conditions. To achieve the delayed boundary condition, I used expressions to define the boundary condition.

The issue I am facing is that the velocity is initially set to zero, which leads to reverse flow occurring in the channel—a behavior that should not happen. I need to ensure that no flow occurs in the channel until the velocity inlet boundary condition is triggered. I have also tried using an outflow boundary condition instead of a pressure outlet, but the problem persists. Additionally, I experimented with mass flow inlet and mass flow outlet boundary conditions, but the issue remains unresolved.

Could someone please help me in solving this issue?

Thank you!

 

[Rob]

How much incomig mass are you seeing? 

[Sravan B]

Inlet mass flow rate is 0.008kg/s. 

If you are asking about how much reverse flow is occuring, in the console it is showing reverse flow in 65% area due to pressure outlet.

[Rob]

Does material density change with temperature? 

[Sravan B]

For PCM, density changes with temperature. For liquid(Water is used), everything is constant.

[Rob]

OK, so if the PCM changes volume (that's another consideration as it can't move) where does the other material (liquids) go?