[ikki9001]

Hi everyone,


I need to calculate via Fluent the cooling of a 1300 K titanium sample immersed in a fluid that flows at 300 K (and therefore the heat exchange between them) for a transient of 15 seconds. By doing the simulations, in addition to having set the boundary conditions, through Cell Zone Conditions, I see that I can only set a fixed value of the temperature, so the simulation only shows me how the fluid warms up, and not how the specimen cools.

Through the named expression I tried to set up a cycle of this type and defining:

TStart = 1300 [K]


TTarget = 1000 [K]

TMin = Minimum (TotalTemperature, ["heatcube"]

TCurrentCube = Average (TotalTemperature, ["inlet"], Weight = None) {inlet = 300 K}

TAdjust = TCurrentCube + (TTarget-TMin) * relax {relax = 0.9}

TCube = IF (iters_per_timestep <10, TStart, IF (mod (iters_per_timestep + 1,30) == 0, TAdjust, TCurrentCube)) {iter / time step = 30 in Run Calculation}

And I impose TCube in the Boundary Conditions -> Wall -> {for all the walls adjacent to the specimen}.

but this method doesn't work and I don't know how to implement it on UDF. I have also tried using the patch command in Initialize, but the specimen temperature still doesn't decay. Can anyone kindly help me?

regards

ikki

[MKuhn]

I would do it in this way. Start with a steady state solution. The cold titatnium sample in the 300 K flow, solve until convergance. Then switch to transient, go to the initialization panel and patch only the temperature of the titanium cell zone to 1300 K - start the simulation with small time steps. In this way the temperature of the titanium will decay and you do not need an UDF.

[ikki9001]

Hi MKuhn,

I'll try your step. Thx very much