**** Entered By: akpaul @ 05/12/2005 10:20 AM ****
Q. I want to specify an entrance region that has laminar flow, which flows into a fully turbulent region?
A. This can be done using the 'Turbulence Transition Model' feature. (Additional licenses may be required). Users can specify laminar and turbulent regions by using the 'Zero Equation' (prescribed intermittency) option of the 'Transition' model. The intermittency can be prescribed as a function of x, y, z coordinates using CEL expressions or a USER FUNCTION. When intermittency = 0, the flow is laminar and when intermittency = 1, flow is fully turbulent.
Example below shows the CCL options for setting a prescribed intermittency transition model. The intermittency is defined by a user function, which returns 0 (laminar) or 1 (turbulent) based on geometric location. (NOTE: At 5.7 and 5.7.1 releases the transition model options can only be setup by editing CCL in PRE or using a text editor. There are no GUI buttons to turn ON transition model)
FLUIDS MODELS:
TURBULENCE MODEL:
Option = SST
TRANSITIONAL TURBULENCE:
Option = Specified Intermittency
Intermittency = TRANSITION TRIP(x,y,z)
END
END
END
CEL:
FUNCTION: TRANSITION TRIP
Option = User Function
Argument List = [m],[m],[m]
Result Units = []
END # FUNCTION
END
USER ROUTINE DEFINITIONS:
USER ROUTINE: TRANSITION TRIP
Option = User CEL Function
Calling Name = transition_trip
Library Name = transitiontrip
Library Path = /myhome/UserSource/
END
END
Full details and options for the transition model is available in the attached PDF file.
**** Entered By: akpaul @ 05/12/2005 10:20 AM **** Q. I want to specify an entrance region that has laminar flow, which flows into a fully turbulent region? A. This can be done using the 'Turbulence Transition Model' feature. (Additional licenses may be required). Users can specify laminar and turbulent regions by using the 'Zero Equation' (prescribed intermittency) option of the 'Transition' model. The intermittency can be prescribed as a function of x, y, z coordinates using CEL expressions or a USER FUNCTION. When intermittency = 0, the flow is laminar and when intermittency = 1, flow is fully turbulent. Example below shows the CCL options for setting a prescribed intermittency transition model. The intermittency is defined by a user function, which returns 0 (laminar) or 1 (turbulent) based on geometric location. (NOTE: At 5.7 and 5.7.1 releases the transition model options can only be setup by editing CCL in PRE or using a text editor. There are no GUI buttons to turn ON transition model) FLUIDS MODELS: TURBULENCE MODEL: Option = SST TRANSITIONAL TURBULENCE: Option = Specified Intermittency Intermittency = TRANSITION TRIP(x,y,z) END END END CEL: FUNCTION: TRANSITION TRIP Option = User Function Argument List = [m],[m],[m] Result Units = [] END # FUNCTION END USER ROUTINE DEFINITIONS: USER ROUTINE: TRANSITION TRIP Option = User CEL Function Calling Name = transition_trip Library Name = transitiontrip Library Path = /myhome/UserSource/ END END Full details and options for the transition model is available in the attached PDF file. 

