TAGGED: boundary-condition, convection, convergence, meshing, transientthermal
April 6, 2023 at 2:54 amChun-Wei TsaiSubscriber
I am doing transient thermal analysis of jetfuel for long haul flight, I have set the boundary condition of walls with heat transfer coefficeint of 15 and temperature of -56.5degree C. And the initial temp. of jetfuel inside being 15degree celcius, the results doesnt really make sense as I expected the temperature would cool from outside to inside gradually. The I have set jetfuel properties with the default piecewise polynomial defalt for jet a 1 from the database and turn the gravity on. Also I have chosen laminar ,energy model for the simulation.
April 6, 2023 at 2:56 am
April 6, 2023 at 2:56 am
April 6, 2023 at 9:00 amRobAnsys Employee
And density varies with temperature in a closed domain? Where is the extra volume coming from or going to?
April 6, 2023 at 2:06 pm
April 6, 2023 at 2:14 pmRobAnsys Employee
If it's constant density you'll not see any convective mixing. Just diffusion & conduction. With changes in density you also need to account for volume: there's a reason for the Bousinesq approximation.
April 6, 2023 at 9:55 pmChun-Wei TsaiSubscriber
Thank you for your answer!! If I'd like to use density change, what kind of change in my model would you recommend? Will it be much more complex? Or do I just need to leave some empty space
April 11, 2023 at 10:30 amRobAnsys Employee
You'd either need Bousinesq (read for why) or add a pressure boundary somewhere to let the solver add/remove a tiny amount of mass to balance the volume.
Leaving a "space" would require a multiphase model, and that's another layer of complexity that you may not want, or need, at present.
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