Defining two ambient temperatures in FlothermXT

pablojoaquim · April 26, 2018, 17:23

Hi everyone! This is my first post in the forum!
I'm Systems Engineer in a company located in Argentina. We develop and manufacture automotive products, and now I'm working in determining the power dissipation of one of our products.
We always work with a unique ambient temperature, but now our customer is asking us about performing a simulation with two ambients.
The product is located in such a way that the backend (the chassis which works as the heatsink) is inside the automotive dash pannel (70ºC), while the frontend (plastic ABS and some circuitry) is in the habitacle temperature domain (35ºC).
Anyone could help me in how to define this condition in FlothermXT? I couldn't find an easy way to do this...

DB99 · January 7, 2019, 23:20

Use a two fluid model as if it were a heat exchanger, and copy Air material to Air2 material using one material on either side.

Use Pressure boundary "lid" to either side. FloTHERM XT can apply pressure boundary but not provide gravity gradient so the pressure on that boundary will not vary with elevation. Can cause problems in resultant flow field if using natural convection.

simple brute force method: make makeshift inlet manifold with surface surrounding it at constant temp. If manifold is long enough the outlet air of the manifold (inlet air to your model), inlet to either side of your dashboard, will be at the prescribed surface temp.

April 26, 2018, 17:23	Defining two ambient temperatures in FlothermXT	#1
pablojoaquim New Member Pablo Joaquim Join Date: Apr 2018 Posts: 1 Rep Power: 0	Hi everyone! This is my first post in the forum! I'm Systems Engineer in a company located in Argentina. We develop and manufacture automotive products, and now I'm working in determining the power dissipation of one of our products. We always work with a unique ambient temperature, but now our customer is asking us about performing a simulation with two ambients. The product is located in such a way that the backend (the chassis which works as the heatsink) is inside the automotive dash pannel (70ºC), while the frontend (plastic ABS and some circuitry) is in the habitacle temperature domain (35ºC). Anyone could help me in how to define this condition in FlothermXT? I couldn't find an easy way to do this...

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January 7, 2019, 23:20		#2
DB99 New Member DB Join Date: Jan 2019 Posts: 28 Rep Power: 7	Use a two fluid model as if it were a heat exchanger, and copy Air material to Air2 material using one material on either side. Use Pressure boundary "lid" to either side. FloTHERM XT can apply pressure boundary but not provide gravity gradient so the pressure on that boundary will not vary with elevation. Can cause problems in resultant flow field if using natural convection. simple brute force method: make makeshift inlet manifold with surface surrounding it at constant temp. If manifold is long enough the outlet air of the manifold (inlet air to your model), inlet to either side of your dashboard, will be at the prescribed surface temp.