1 Reply Latest reply on Jan 14, 2013 8:48 AM by Bill McEachern

Where is the limit of Flow Simulation in vacuum (space)?

Isaac Llorens Jan 13, 2013 1:50 PM

Hi,

I am developing a cold gas propulsion system for space. At the moment I am working in a nozzle for the system.

I need to know the limits of SolidWorks Flow Simulation. In my case I need to do the simulations in space conditions (vacuum) but Flow Simulation doesn’t allow vacuum.

I had realize some simulations using an environment conditions of 1x10^-5 Pa but the results obtained are not physically consistent.

Does anyone know if exists a range of environmental pressure where the simulations lost consistence? How can I simulate a vacuum environment without losing physically consistence?

For more details this is and schematic example of my simulation

Re: Where is the limit of Flow Simulation in vacuum (space)?

Bill McEachern Jan 14, 2013 8:48 AM (in response to Isaac Llorens)

In rarefied flows the navier-stokes equations are no longer valid when the mean free path is in the some order of magnitude as the domain of internest. that is to say the continumm approximation to reality is not longer valid. The general idea here is if the Knudsen number is greater than 1 then statistical methods need to be employed. You can try here: http://en.wikipedia.org/wiki/Knudsen_number or look up rerefied flows in wikipidia or some other reference. So it depends what you are looking at but it is a plce to start. Good luck.
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