CFD with floworks

[Paul Dansereau]

Hi All,
I am trying to model the flow through our venturi with Floworks 2000, the solidworks add-on package and I'm getting bad results. I am modeling it as internal flow with an inlet volume flowrate and and external volume flowrate that are the same (0.1 m^3/s). I don't have alot of experience and any help would be appreciated as the help file sucks.

Cheers,

ojpd

[Brent Howard]

Define Bad

I've been ding a bit of work on flow works in the past few days to model our plenum and runners, so if you want to figure this stuff out contact me tonight at howard_brent@hotmail.com on MSN or if not e-mail me and I can try to give you a hand.

Brent

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Belo]

I'm presently doing the same thing, What I do is I simulate a pressure opening on the air filter side... with atmospheric conditions...

On the engine side, I put an outlet volume flow... I then rise it until the venturi is choked... not sure yet if it s the right way but it seems to work well...

Alex

[osubeaver]

Use a pressure boundary condition. BTW, flowworks is shady business.

[BeaverGuy]

Definitely use a pressure boundary condition on both sides of the restrictor. FloWorks will get the job done but you need to be sure you know what you are doing. It is definitely easier to use than star-CD but that also makes it easier to make mistakes. You also need to make sure you are running compressible flow. While the basic version of FloWorks incorporates all flows up to Mach 3 as one selection the Proffesional Edition requires it for values above 0.3. It makes a big difference in the equations the program is solving.

I would say the bad results he is getting are Mach Values above 1 at the throat. He is forcing more air through the restrictor than is possible in a standard system. Essentiall he is modelling a dual throat system like an aircraft inlet traveling above Mach 1. If you want to try something other than a pressure boundary condition use a mass flow at the inlet and don't go above about 70 g/s. Don't use a mass or volume flow at the exit because there will likely be recirculation due to the flow becoming detateched from the walls and outlet flows do not like this.