Discussion ClosedThis discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one,click here.
k-epsilon in rough pipes
Posted 2009年7月21日 GMT+2 20:030 Replies
Please login with a confirmed email address before reporting spam
Hi, I am modelling high velocity gas entering via a porous media into a tube. I'm using the leaking-wall formulation in COMSOL k-epsilon. Hotter gas enters near the bottom of the tube and cooler gas enters half-way up. Reynolds about 1.e5 - 1.e6.
Somewhat to my surprise, the resulting turbulent kinetic energy is quite low along the pipe. As a corollary, at the top of the pipe I have more of a radial gradient in temperature than I would have expected: the hotter gas stays in the middle of the tube and takes a distance (many diameters) to reach equilibrium with the cooler gas.
My dwplus_chns is about 400 so I think I've meshed the inside of the tube well enough.
I wonder if it is the smoothness of the pipe which is keeping turbulence down....? Is there a simple way to add a rough-wall friction factor to the k-epsilon wall boundary condition?
Regards, John
Somewhat to my surprise, the resulting turbulent kinetic energy is quite low along the pipe. As a corollary, at the top of the pipe I have more of a radial gradient in temperature than I would have expected: the hotter gas stays in the middle of the tube and takes a distance (many diameters) to reach equilibrium with the cooler gas.
My dwplus_chns is about 400 so I think I've meshed the inside of the tube well enough.
I wonder if it is the smoothness of the pipe which is keeping turbulence down....? Is there a simple way to add a rough-wall friction factor to the k-epsilon wall boundary condition?
Regards, John
0 Replies
Last Post 2009年7月21日 GMT+2 20:03
Hello John
Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.
If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.