Fluids

Wall boundary condition (Convection heat)

• Daicha
Subscriber

Hello Experts.

In my simulation, I would like set convection heat boundary condition at wall boundary (2D simulation)

So, heat flux at boundary can be expressed as following equation.

q =h*(T(outside)-T(fluid))

where q : heat flux from wall to fluid [w/m2], h: Convection Heat Transfer coefficient [W/m2 K], T(outside): Wall temperature, [K]

T (fluid): Fluid cell temperature next to wall [k]

According to fluent user's guide, this setting can be set at fluent's (boundary condition→ thermal→convection boundary condition)

So i did this setting However, the amount of heat flux was lower than I imagined.

So my  questions are

1. Are any problems in terms of heat flux caused if i simulate under 2D, cylinder symmetry, millimeter, condition ?

2. In the setting page of convection boundary condition, we can set heat generation rate [W/m3]. How is this value used for heat flux calculation ? (If possible, I would like you to indicate the specific equation )

Best Regards

• DrAmine
Ansys Employee

1/Should work: if 2D think about the reference depth you need to adjust to get the heat flux (W)

2/That is another thing and you can think about it as a volumetric source for the wall which now requires a finite thickness