Reverse Flow

Amrita Shukla · March 21, 2015, 02:46

How to remove reverse flow problem? According to the posts on forum pressure outlet condition creates this problem . So i changed the condition to outflow but still i am having reverse flow problem.

`e` · March 21, 2015, 06:57

What geometry are you simulating? Have you allowed fully developed flow upstream and downstream etc?

hwet · March 21, 2015, 07:41

increase the length towards the outlet so the flow can be established, post your geometry here if possible

Amrita Shukla · March 21, 2015, 11:13

Quote:

Originally Posted by `e`

What geometry are you simulating? Have you allowed fully developed flow upstream and downstream etc?

I am simulating an EGR cooler. It is a shell and tube HX. I know the mass flow at inlet and temperatures.

How to allow fully developed upstream/ downstream. Sorry,I am new at this.

Amrita Shukla · March 21, 2015, 11:16

The length of the geometry is fixed. Cannot do that

`e` · March 21, 2015, 17:07

Surely you can model further upstream and downstream (post your geometry), we're not asking you to modify the critical HX section.

vasava · March 23, 2015, 01:29

'e' has already explained that your outlet is too close for your outlet flow to be resolved.

I would like to add that the reverse flow is just a warning and not an error. If you havent used a proper initial guess it will persist for number of iterations depending on how complex is your flow is. Also it may be indicating flow re-circulation in that region.

March 21, 2015, 02:46	Reverse Flow	#1
Amrita Shukla New Member Amrita Join Date: Mar 2015 Posts: 3 Rep Power: 11	How to remove reverse flow problem? According to the posts on forum pressure outlet condition creates this problem . So i changed the condition to outflow but still i am having reverse flow problem.

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March 21, 2015, 06:57		#2
`e` Senior Member Join Date: Mar 2015 Posts: 892 Rep Power: 18	What geometry are you simulating? Have you allowed fully developed flow upstream and downstream etc?

March 21, 2015, 07:41		#3
hwet Senior Member Join Date: Mar 2014 Posts: 375 Rep Power: 13	increase the length towards the outlet so the flow can be established, post your geometry here if possible

March 21, 2015, 11:16		#5
Amrita Shukla New Member Amrita Join Date: Mar 2015 Posts: 3 Rep Power: 11	The length of the geometry is fixed. Cannot do that

March 21, 2015, 17:07		#6
`e` Senior Member Join Date: Mar 2015 Posts: 892 Rep Power: 18	Surely you can model further upstream and downstream (post your geometry), we're not asking you to modify the critical HX section.

March 23, 2015, 01:29		#7
vasava Senior Member Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 732 Rep Power: 22	'e' has already explained that your outlet is too close for your outlet flow to be resolved. I would like to add that the reverse flow is just a warning and not an error. If you havent used a proper initial guess it will persist for number of iterations depending on how complex is your flow is. Also it may be indicating flow re-circulation in that region.