CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

Mass loss in exported inlet profile

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   April 14, 2013, 03:11
Default Mass loss in exported inlet profile
New Member
Riza Yukananto
Join Date: Mar 2013
Posts: 4
Rep Power: 6
Pheasants is on a distinguished road
Hi guys,

I'm simulating a combustion in a combustor chamber with fluent.
Since the combustor's geometry is big, I divided the simulation into cold flow for the whole geometry, and later on hot flow for only small part of the geometry.

I exported the boundary profile from the result of the cold flow simulation (omega, k, v-x,y,z) with CFD-post, at some surface location (made with plane and surface revolution) , and use it as velocity inlet profile for the hot flow simulation at the exact same location.

Now, the intended convergence level is not yet satisfied, but there is apparent decrease in the mass flow rate (initially inlet mass flow rate was 0.0375 in, but after it was exported at several cutting location, it decreases into 0.0369).

Can anybody tell me why is this happening?

Thanks a lot guys.
Pheasants is offline   Reply With Quote

Old   April 15, 2013, 06:43
New Member
Riza Yukananto
Join Date: Mar 2013
Posts: 4
Rep Power: 6
Pheasants is on a distinguished road
Hello guys..

Apparently the incorrect mass flow is coming from the cfd-post itself..

The massflow difference between inlet and outlet is less 0.0002% (which basically, no difference)..

But when I Define a surface, for example, 5cm from the inlet surface (with the same area), and then I calculate the massflow, the value changes.. and the massflow difference between the inlet and the newly defined surface is 0.8%, which is ridiculously huge..
If I define another surface, say now its 10 cm from the inlet, the mass flow changes again..

Do anybody know why was this happening? was it because the hybrid or conservative value used by the fluent solver?

thanks a lot guys.
Pheasants is offline   Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
How to define a fixed velocity for a given mass flow rate on inlet mqasimali FLUENT 2 April 12, 2013 17:24
Pulsatile profile at inlet Josyula Fluent UDF and Scheme Programming 4 May 6, 2012 10:09
Net mass flow inlet vs outlet Nigui28 FLUENT 1 August 12, 2011 10:09
Pressure Inlet Boundary Condition Profile arapha FLUENT 0 April 4, 2011 16:23
reversed flow at velocity inlet / mass flow inlet ib FLUENT 1 March 26, 2007 13:11

All times are GMT -4. The time now is 22:21.