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-   -   Internal flow simulation boundary conditions (http://www.cfd-online.com/Forums/fluent/45226-internal-flow-simulation-boundary-conditions.html)

Kishore July 2, 2007 02:12

Internal flow simulation boundary conditions
 
hi, need ur suggestions in this prblm Problem description: it is a internal flow simulation through a duct connected to a chamber which has 2 outlets(identical area).the flow is a velocity at inlet is 42 m/s and static pressure is 1.2 bar with T= 298 k. outlet conditions are not known. pressure drop from inlet to outlets is not known.

method i tried for simulating and getting conditions at outlet is as follows : i gave velocity inlet and 2 outflows and computed the static pressure using area weighted average option for the two outlets. then in the second simulation i gave this static pressure at outlet and 1.2 bar at inlet with pressure inlet and pressure outlet boundary conditions. my query: is this simulation physically correct to determine the outlet conditions? because when initializing before iterating , the inlet velocity which fluent computes and gives for initialization is nearly 3 times (150 m/s). kindly help in this...

Chx July 10, 2007 11:42

Initialization with UDF
 
Using FLUENT, I am trying to generate a regular wave in a 2d domain by specifying a transient velocity profile at my inlet. The top and end of my domain are pressure outlets with atmospheric pressure and hydrostatic pressure specified for both boundaries respectively. Gravity is acting in the negetive y direction and based on my UDF, I expect maximum velocities of 1.7m/s but when initializing before iterating , the inlet velocity which fluent computes and gives for initialization is nearly 17 times (28 m/s). I have looked at and had many guys look at my UDF over and over again and can't find anything wrong with it. Any body has an idea where the problem could be?


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