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The relation between mesh size and time step in time-dependent study on heat transfer problem

Posted May 13, 2016, 12:03 p.m. EDT Heat Transfer & Phase Change, Mesh, Studies & Solvers Version 5.1, Version 5.2 1 Reply

Li-Fan Yang
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Dear all,

I am simulating heat transfer problem and when it comes to set up the mesh, is there a limit on the max mesh size according to the time step I set up? Say I compute the heat transfer and want to see the temperature distribution in the material each 1ms, is there a requirement for the mesh size due to this condition (or the velocity that heat travels)?

Thanks.
1 Reply Last Post Mar 30, 2017, 8:46 a.m. EDT
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Hello Li-Fan Yang

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Antoni Artinov
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Posted: 8 years ago Mar 30, 2017, 8:46 a.m. EDT
Hi,

The realtion between mesh size and time step in transient heat transfer study is defined by the thermal diffusivity. This is the heat propagation "speed" through the material. If the conductivity of the material is quite small, the heat will propagate less into the body and if this depth is of the order of the element size, you will get oscillations in the temperature profile, because you can not capture the solution. The critical time step is a direct result of the non-dimensionalization of the heat transfer by the conduction equation: L=sqrt(k*dt/(rho*Cp)).

See:
pruffle.mit.edu/3.016/Appendices/NonDimensional.pdf

Best regards,
Antoni


Hi, The realtion between mesh size and time step in transient heat transfer study is defined by the thermal diffusivity. This is the heat propagation "speed" through the material. If the conductivity of the material is quite small, the heat will propagate less into the body and if this depth is of the order of the element size, you will get oscillations in the temperature profile, because you can not capture the solution. The critical time step is a direct result of the non-dimensionalization of the heat transfer by the conduction equation: L=sqrt(k*dt/(rho*Cp)). See: http://pruffle.mit.edu/3.016/Appendices/NonDimensional.pdf Best regards, Antoni

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