[rowny]

Hello everyone!

I have the following problem:

Let's consider a pipe that evolves into a complex geometry. We can calculate Re in the pipe, based on its dimensions, but we cannot use this expression for the rest of the geometry.
Can I instead do the following: Use a uniform mesh across the whole geometry (equally-sized elements) and then look at the values for Cell Reynolds number, and then compare the values in the geometry to the values in the pipe, and estimate how many times the turbulence increases outside of the pipe? If it is, let's say, 10 times, and I know that I have Re=4000 (from expression) in the pipe, can I state that I have Re=40000 in the geometry?

thanks!

[FMDenaro]

Originally Posted by rowny

Hello everyone!

I have the following problem:

Let's consider a pipe that evolves into a complex geometry. We can calculate Re in the pipe, based on its dimensions, but we cannot use this expression for the rest of the geometry.
Can I instead do the following: Use a uniform mesh across the whole geometry (equally-sized elements) and then look at the values for Cell Reynolds number, and then compare the values in the geometry to the values in the pipe, and estimate how many times the turbulence increases outside of the pipe? If it is, let's say, 10 times, and I know that I have Re=4000 (from expression) in the pipe, can I state that I have Re=40000 in the geometry?

thanks!

No, the cell Re number is a computational parameter, it is not meaningful of the global Re number based on the integral lenght scale....if you diminuish the cell size your cell Re dimuishes according to the grid size but the physical problem remains the same.
Chose the integral lenght (for example the size of the pipe) to estimate the Re in pipe or use the characteristic lenght of a body (if present) in the rest of the geometry.