[michellemay1993]

Hi, I am a degree student. I was wondering how to calculate the average mass flow rate over the total time step at outlet.

[evcelica]

1.) Make An Expression for MyOutFlow = "massFlow()@outlet"
2.) Make a chart where you plot the transient results for this expression
3.) export it as .csv and average it in excel or some other program.

There may be another way using transient statistics, but I have not done it that way, so I can't tell you how.

[michellemay1993]

Is this how it normally be calculated?

[Opaque]

A modified version of Evcelica instructions:

If you are using CFD-Post :
1.) Make An Expression for MyOutFlow = "massFlow()@outlet"
2.) Make a chart where you plot the transient results for this expression
3.) In the Data Series tab, there is an info (i) icon (just below the (x) for delete). Click the info icon, and it will display the max/min/mean over the rang of the chart. There is just "time averaged value"

If you are using a recent version of ANSYS CFX, you can use the ANSYS CFX Solver Manager,

1.- Create a plot for the Boundary Flow for the continuity equation at the Outlet (effectively massFlow()@outlet).
2.- Create a Derived Variable for such plot (right click on the plot area), and look at the Derived Variables tab. Select the type of statistics you want to evaluate, say Time Average. Select the range of time for the averaging.
3 - Go to the Plot Variables tab, and activate on which individual plot you want the statistics to be computed; otherwise, it will compute on all the variables being plotted.

If you want for the quantities to be computed in the solver, and output to the ANSYS CFX Solver Manager,

1.- Create a monitor point
2.- Select Option = Expression, write the expression of interest
3.- Activate Transient Statistics for that expression and select the statistics of interest..

As you see, there are several ways to obtain what you need.

Hope the above helps,

[dboss]

@Opaque
I tried the last possibility you mentioned. But I couldn't find the averaged massflow in the cfx solver manager?

[Opaque]

The last option is to be set in CFX-Pre(processor), and visualize in the CFX-SolverManager

In CFX-Pre, goto Output Control/Monitor, insert Monitor Point-> Option=Expression, and you should see what is available to you.

[dboss]

I am not sure if understood your description correctly.


At the moment I have a area averaged massflow for which I defined a monitor point in cfx-pre. During solving in the cfx-solver I can see on a monitor the reasonable fluctuating curve for the massflow.


But how can i extract the average out of this curve?


I already tried by creating a trn-stats document in cfx-pre with arithmetic average, a specially created variable massflow, but I couldn't find the result chart, file or table?


Thank you for your patience.

[Opaque]

Could you post the CCL for the monitor point you have created?, Right click on the monitor point icon in the Outline tree, select Edit in Command Editor, copy and paste here.

[dboss]

FLOW: Flow Analysis 1 OUTPUT CONTROL:
MONITOR OBJECTS:
&replace MONITOR POINT: massflowinletleft
Coord Frame = Coord 0
Expression Value = massFlowInletLeft
Option = Expression
END
END
END
END

[Opaque]

What is your expression for massFlowInletLeft equal to?

[dboss]

massFlowInletLeft is equal to massFlow()@REGION:inlet_left


CCL would be:



LIBRARY: CEL:
&replace EXPRESSIONS:
Nperiod = 10
PexiteAmpl = 50000 [Pa]
PexiteMean = 200000 [Pa]
Pout = 1e5[Pa]
Tin = 293[K]
freqO = 1000 [Hz]
massFlowInlet = massFlow()@REGION:inlet
massFlowInletLeft = massFlow()@REGION:inlet_left
massFlowInletRight = massFlow()@REGION:inlet_right
massFlowOutlet = massFlow()@REGIONutlet
pInletLeft = massFlowAve(Absolute Pressure )@REGION:inlet_left
pOszileft = PexiteMean + PexiteAmpl *sin(2*pi*freqO *t)
pOsziright = PexiteMean + PexiteAmpl *cos(2*pi*freqO *t)
pin = 5e5 [Pa]
timeStepsPerPeriod = 40
END
END
END

[Opaque]

I assume you are using a recent version of the software; therefore, the following should work

FLOW: Flow Analysis 1 OUTPUT CONTROL:
MONITOR OBJECTS:
&replace MONITOR POINT: massflowinletleft
Coord Frame = Coord 0
Expression Value = massFlowInletLeft
Option = Expression
MONITOR STATISTICS:
Option = Moving Interval
Statistics List = Arithmetic Average
INTERVAL DEFINITION:
Number of Timesteps = 10
Option = Timesteps
END
END
END
END
END
END

[dboss]

Sorry for the late response. That did work thank you very much.