[Raddy]

I'm working on a simple heat transfer project (convection over a flat plate) and I was wondering if it's possible for FLUENT to calculate the temperature of the wall as time progresses. I have done some transient analysis, but in each simulation, the temperature of the wall does not change. My theoretical calculations put the total cooling time (from starting temperature to ambient temperature) at around 200 seconds, but I've done simulations as long as a few hours of cooling and the plate temperature won't change. Is this possible to model in FLUENT, and if so, what boundary/initial conditions will I need? Thank you for any help you guys might have.

Some problem parameters:

298 K air blown at 20 m/s over a ceramic plate (physical properties known) at 647 K
The plate does NOT generate heat; i.e., it was in an oven and is now being cooled
Flow is assumed to be laminar (for now)

If you don't have specific instructions, even a tutorial with a similar situation would be greatly appreciated.

[zhaopeng]

Did you report the change of temperature by surface monitor?You can examine the temperature distribution by report contours,if it is not change after several time steps,there must be some problem in your model.

And is the ceramic plate at 647K in contours of temperature before you start interation?I think there is a lack of initial conditions in your model.

[Raddy]

Here's the geometry (mesh invisible)...the gray sides are the inlet (velocity_inlet) and outlet (pressure_outlet), the plate (wall) is at the bottom, and the rest of the walls were defined as symmetry.



Okay, I've tried it again and here's what I did to setup the problem:

Solver > Time > Unsteady, all others left at default
Energy > Enabled

Boundary Conditions:
Wall > Thermal > Properties > Density = 890, Specific Heat = 1600, Thermal Conductivity = 1.5
Wall > Thermal > Temperature > Temperature = 647 K

Velocity Inlet > Thermal > 298 K
Velocity Inlet > Momentum > 20 m/s

Pressure Outlet > Thermal > 298 K

Solve:
Solution Controls > Pressure-Velocity Coupling > SIMPLEC; skewness correction = 1
Solution Controls > Pressure > Standard
Solution Controls > Momentum > QUICK
Solution Controls > Energy > QUICK

Initialize > Compute From > inlet; X-Velocity = -20 m/s; Temperature = 298 K

Monitors:
Surface Monitor > Plot = True; Print = True; Report Type = Area-Weighted Average; X-Axis = Time Step; Surface = wall; Report of = Temperature...Static Temperature;

Iterate:
Time Step = 1 second
Number of Time Steps = 500 seconds
Max Iterations per step = 5

The plate temperature would not change...I also tried setting the thermal conditions for the plate for convection and giving it a convection coefficient I calculated and setting the freestream temperature to the temperature of the air. This varied plate temperature with time, but the initial plate temperature was 298 K. So I tried initialize the plate instead of the inlet, setting the temp to 674 K and all the velocities to zero. This again produced time-varying temperature, but still not at the initial 674 I specified. How should I go about setting this up?

[zhaopeng]

it is right to set the thermal conditions of the plate for convection,you may need to patch the temperature of plate to 647K before starting interation.