Queries Regarding pipe flow

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hello Guys,

I was working on my project, for that I have just started with a very simple pipe flow. I have few queries regarding the same and I would be grateful if you will help me to answer my queries.

The dimensions of the model pipe are 10 mm in diameter and 25 mm in length. I have done modelling in in Creo Parametric 2.0.

When importing this file in Acuconsolve, (at the very first stage) a dialog box opens where I only change the units to 'm' from 'mm'.
Now i have defined the inlet, outlet and wall for the model.
At inlet I have defined as Average velocity = 10m/s.
A outlet as outlet and wall as wall.


In volume the material model is used as water.
For problem description analysis type is steady state, flow equation is Navier stokes and all the other things are set as it is in default(also for auto solution strategy.

Now I have done the volume meshing and run the solver.

Now while plotting the results for velocity magnitude and pressure, I am getting very unrealistic answer, like the velocity is 20.474 and the pressure is 7951.421.(I have attached the files)

I am not getting to what formula does solver based??
how it calculates the velocity magnitude and pressure??

If for pipe flow we use a simple equation like ..
(Flow at inlet = flow at outlet)
Then , A1*V1 = A2*V2
Then the Area will be same which gives the velocity as 10m/s, as i have defines the v1= 10m/s as per my analytical calculation.

Regarding for the pressure values also I want to know the calculations, weather it accounts for total pressure or only the static pressure.

Total pr = Static + Dynamic + (row*g*h)[neglecting this term for our case]
Total p. = Pstatic + (0.5*row*(v)^2)

Then also I am not getting the results which i am calculating theoretically.

1.) I also want to know about the inlet conditions that, what can be used for pipe flow, (mass flux, average velocity, flow rate or simply velocity in any axis.).
2.) Formula for calculating velocity and pressure.
3.) Losses are being considered in this pipe or not??
4.) Should I change the units in the beginning to 'm' or not while importing the model.(as creo parametric based on millimeter newton seconds. so every dimensions of the model are in 'mm' only.

With best regards and Thanks,

Swapnil

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Answers

  • ydigit
    ydigit
    Altair Employee
    edited July 2015

    How many nodes do you have across the diameter of the pipe? The nodes at the edge of inlet surface would have 0m/s.

    With 10mm pipe and 10m/s, you would also need to check if the Yplus values are below 300.

     

    -Inflow pull down menu lists the BCs that can be used for Inflow: (mass_flux, avg vel,vel components, vol flow, Stagnation pressure,etc)

    -Nodal output from AcuSolve is static pressure. 

    -Log file gives you the maximum and minimum coordinates. This can be used to check if you imported correctly. AcuConsole : Right click Volume, Info also gives this information.

     

    Could you share the .INP and .Log file, Screenshot of mesh at inlet and section cut?

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