Linear heat conduction in plate.
Hello,
I tried to verify my linear heat conduction simulation results with theoretical results but facing problem.
These are the input of problem & theoretical solution-
Q = K. dT/dx
Q = 12e^6 watt/m2
K = 40 watt/m.K
dx = 2 mm = .002
12000000 = 40* dT/ .002
dT = 600 K
So my temperature value should be 600 K.
For same i'm using optistruct but results are quite far from theoretical one. As shown in image below.
(I converted MKS unit in mm, Mg, sec during modelling).
Plz let me know where i'm wrong ?
<?xml version="1.0" encoding="UTF-8"?>
Answers
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Temperature boundary condition is missing in your hm file.You can refer OptiStruct online tutorial OST-1085 and can download free ebook on Thermal analysis with OptiStruct using below link.
https://altairuniversity.com/free-ebook-thermal-analysis-with-optistruct/
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Hello Rahul,
As i mentioned that i'm comparing theoretical results with simulation, In theory there is no need of applying constrained for such condition. Its direct formula based problem. Put the value & get dT.
My problem is just to know the temperature in plate of some thickness from which flux is passing. Again here problem same as my previous question (Thermal stress Analysis), that if theoretically there is no need to apply constraints then why it needs in CAE (optistruct).
Even software not showing any warning for it.
However, current results are far far away from theoretical.
Plz solve the issue.
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One needs to define the thermal boundary conditions on the structure. Otherwise, the heat convection and conduction won't happen. There has to be some temperature difference to initialize the heat transfer. It is like we want to do a linear static analysis but only knowing about the loadings.
The user needs to provide the info about the temperature on the structure.<?xml version="1.0" encoding="UTF-8"?>
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Hello,
The equation (Kc+H) T = f is compact form of Q = K. dT/dx
In our case H = 0 (no convection)
Where f is nothing but Q.dx (power due to heat flux).
Of course LHS matrix will singular if we not apply any of fB, fH, fQ. But here i defined flux in my case so fQ should be non zero & above equation is non singular matrix.
There should be proper results by solver in case.
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Output which you are currently getting is because of singularity(6.7 e17 from screenshot shared by you).I think not considering surrounding temperature is violating the law of thermodynamics. Just consider the surrounding temperature of let say 25 degree c or 298K will make difference in the output.
<?xml version="1.0" encoding="UTF-8"?>
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Hello Rahul,
Sorry for late reply. As i can see model upload by u having constrained in one edge with temp 298 K.
1. This problem will be different from the case that i mentioned at start. Ur constraints behave like sink of some temperature, whatever flux we apply it always maintained 298 K temp on that edge.
2. Point to be notice that if we r talking about conduction & component temperature due to flux only (no convection & radiation BC's), we need not to worry about surrounding temperature.
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