peglor
Mechanical
- Sep 10, 2002
- 109
I'm wondering what the best way is to model thermal bahaviour in a very long thin channel with heaters fitted outside it using ProMechanica. The channel is about 300microns by 400 microns by 30mm in size.
Fluid speeds will be very low through the channel, so the fluid in the channel is being modelled as a solid. The channel is cut into a block of one material (Not specified yet) and capped by another and there are three heaters covering parts of the underside of the channel.
Initially a 3D model was built (ProEngineer integrated with ProMechanica made this very fast), but as expected, due to the massive aspect ratios involved, particularly in the channel walls (50 microns thick), the number of elements needed for an acceptable mesh was astronomical, especially when the relative simplicity of the model is considered.
What I'm wondering is whether it's possible to model the same thing as a solid in the centre for the fluid in the channel, with 4 shells around it with preset thickness properties to model the boundaries of the channel and heat applied to the back surfaces of the shell at the bottom of the channel to simulate the effect of the heaters.
I don't know how to make ProMechanica deal with heat being applied to one side of a shell and conducting through to the other side. It may be as simple as splitting the shell onto a few different ones and applying the heat load to the correct shells, letting the program assume you've applied the load to the correct side.
Incidentally, 2D models aren't feasible as the heating isn't continuous along the underside of the channel.
Is it possible to use anisotropic heat transfer properties in the materials to allow a lower aspect ratio model to give the same results? This could potentially allow a 3D model to be used.
I've rambled on a bit, but hopefully I've defined the problem well enough. Thanks in advance for any help.
Fluid speeds will be very low through the channel, so the fluid in the channel is being modelled as a solid. The channel is cut into a block of one material (Not specified yet) and capped by another and there are three heaters covering parts of the underside of the channel.
Initially a 3D model was built (ProEngineer integrated with ProMechanica made this very fast), but as expected, due to the massive aspect ratios involved, particularly in the channel walls (50 microns thick), the number of elements needed for an acceptable mesh was astronomical, especially when the relative simplicity of the model is considered.
What I'm wondering is whether it's possible to model the same thing as a solid in the centre for the fluid in the channel, with 4 shells around it with preset thickness properties to model the boundaries of the channel and heat applied to the back surfaces of the shell at the bottom of the channel to simulate the effect of the heaters.
I don't know how to make ProMechanica deal with heat being applied to one side of a shell and conducting through to the other side. It may be as simple as splitting the shell onto a few different ones and applying the heat load to the correct shells, letting the program assume you've applied the load to the correct side.
Incidentally, 2D models aren't feasible as the heating isn't continuous along the underside of the channel.
Is it possible to use anisotropic heat transfer properties in the materials to allow a lower aspect ratio model to give the same results? This could potentially allow a 3D model to be used.
I've rambled on a bit, but hopefully I've defined the problem well enough. Thanks in advance for any help.