Learning Forum

[abdullahhassan]

Helo, I am dealing with a big complex geometry (2m length) and want to perform condensation simulation on it. Majority of paper using around same geometry have around 5M cells to 9M cells. 

My question is:

1- can I scale down a geometry in ansys by factor of 5 or 10 to reduce the computational time. Will it effect negatively on the results of multiphase simulation ?

2- My curiosity is, if the domain scalled down by factor of 5, so the cell size will also be smaller 5 times then normal. does it means the overall number of elements in the domain is not changing and also the computational time remains unchanged. ??

[Rob]

In Fluent we can scale the mesh to change the overall dimension. Common usage is when mm/m/km get muddled in the CAD or someone builds a CAD model in inches. The cell count remains the same and the cell size scales with the mesh. 

Changing the scale may also alter the results; especially if residence time or flow regime changes. If mass flow isn't scaled it definitely will! 

Because the cell count is unchanged the RAM usage is also unchanged. Time step will scale with the domain, but flow residence time may not (that's down to how you scale the boundary conditions) so that could alter the overall run time could reduce. Not a question I can really answer as there are too many variables for a generic answer, and I'd need too much information to be specific.