Fluent flow model

Dr.Sami · May 17, 2014, 10:50

Dear Freinds,

I kindly ask you to help me in my design problem. I use tube in twist tape insert and the input Reynolds number varies between 200-1500. I confused which model shall i use the laminar depending on input reynolds number or turbulent due to to swirl folow induced in side tube becuse of twist tape.

Regards

CFD-fellow · May 19, 2014, 16:05

There is no contradiction between laminar flow and swirling flow. I mean a swirling laminar flow is possible. Also input reynolds number is not a good criterion for turbulence in your case. Just try with laminar first. Supposing high quality mesh, if you couldnt converge your solution with laminar, it means that turbulence is being produced in your domain.
In many cases, with turbulence it is possible to simulate a laminar flow but not in opposite way.

Mohawk · May 19, 2014, 17:02

Use k epsilon it's valid for laminar and turbulent flow

Dr.Sami · May 20, 2014, 08:54

Dear Friends

Greeting, thanks for your reply

with regards

farzadpourfattah · May 20, 2014, 14:53

for low Reynolds Number Flow that experience adverse pressure gradient use Spallart Allmaras model with Y+ less than 1 or
use KW Transition Model (4 Equation model that added in fluent Ansys15) with y+ less than 1.

May 17, 2014, 10:50	Fluent flow model	#1
Dr.Sami New Member sami D. Salman Join Date: Dec 2011 Posts: 2 Rep Power: 0	Dear Freinds, I kindly ask you to help me in my design problem. I use tube in twist tape insert and the input Reynolds number varies between 200-1500. I confused which model shall i use the laminar depending on input reynolds number or turbulent due to to swirl folow induced in side tube becuse of twist tape. Regards

May 20, 2014, 08:54	Fluent flow model	#4
Dr.Sami New Member sami D. Salman Join Date: Dec 2011 Posts: 2 Rep Power: 0	Dear Friends Greeting, thanks for your reply with regards

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May 19, 2014, 16:05		#2
CFD-fellow Senior Member Behrooz Jamshidi Join Date: Apr 2013 Posts: 110 Rep Power: 13	There is no contradiction between laminar flow and swirling flow. I mean a swirling laminar flow is possible. Also input reynolds number is not a good criterion for turbulence in your case. Just try with laminar first. Supposing high quality mesh, if you couldnt converge your solution with laminar, it means that turbulence is being produced in your domain. In many cases, with turbulence it is possible to simulate a laminar flow but not in opposite way.

May 19, 2014, 17:02		#3
Mohawk Member Mustafa Join Date: May 2013 Posts: 54 Rep Power: 12	Use k epsilon it's valid for laminar and turbulent flow

May 20, 2014, 14:53	hi	#5
farzadpourfattah Member farzadpourfattah Join Date: Mar 2013 Posts: 41 Rep Power: 13	for low Reynolds Number Flow that experience adverse pressure gradient use Spallart Allmaras model with Y+ less than 1 or use KW Transition Model (4 Equation model that added in fluent Ansys15) with y+ less than 1.