[m5m5kh]

Dear Foamers

I want to simulate a real blood flow in an aortic aneurysm. I used the paper done by Khanafer et al. entitled "Modeling pulsatile flow in aortic aneurysms:
Effect of non-Newtonian properties of blood"
they used an inlet velocity profile which contains a term of U(t) (please see the attached picture)
Using groovyBC, it is possible to add a parabolic velocity inlet but I don't have any idea how to add a velocity profile term created from interpolation of 350 points. Is there anyone who can help me with this issue?
I will be grateful if you help me with your advice.

Br,
Mohsen

[m5m5kh]

Please share your knowledge with me

[sheaker]

I believe You need to use some tool (excel or something like that) to approximate a formula of Your inlet profile then follow this tutorial
https://www.youtube.com/watch?v=K-nAF3qAPTc

[Tobi]

Hi all,

in OpenFOAM there is a boundary called timeVaryingMappedFixedValue which can handle tables and makes interpolation inbetween the timesteps. The header file of the class states:

Description
    This boundary conditions interpolates the values from a set of supplied
    points in space and time.

    Supplied data should be specified in constant/boundaryData/\<patchname\>/
      - points             : pointField of locations
      - \<time\>/\<field\> : field of values at time \<time\>

    The default mode of operation (mapMethod planarInterpolation) is to project
    the points onto a plane (constructed from the first threee points) and
    construct a 2D triangulation and finds for the face centres the triangle it
    is in and the weights to the 3 vertices.

    The optional mapMethod nearest will avoid all projection and triangulation
    and just use the value at the nearest vertex.

    Values are interpolated linearly between times.

Usage
    \table
        Property     | Description                | Required    | Default value
        setAverage   | Switch to activate setting of average value | no | false
        perturb      | Perturb points for regular geometries | no | 1e-5
        fieldTableName | Alternative field name to sample | no| this field name
        mapMethod    | Type of mapping            | no | planarInterpolation
        offset       | Offset to mapped values    | no | Zero
    \endtable

    \verbatim
    <patchName>
    {
        type            timeVaryingMappedFixedValue;
    }
    \endverbatim

An example is given in $FOAM_TUTORIALS/incompressible/simpleFoam/pitzDailyExptInlet

Good luck,
Tobi

[m5m5kh]

Dear Tobias and Oskar
Thanks for your help.I will follow your hints.

Kind regards,
Mohsen

[m5m5kh]

Originally Posted by Tobi

Hi all,

in OpenFOAM there is a boundary called timeVaryingMappedFixedValue which can handle tables and makes interpolation inbetween the timesteps. The header file of the class states:

Description
    This boundary conditions interpolates the values from a set of supplied
    points in space and time.

    Supplied data should be specified in constant/boundaryData/\<patchname\>/
      - points             : pointField of locations
      - \<time\>/\<field\> : field of values at time \<time\>

    The default mode of operation (mapMethod planarInterpolation) is to project
    the points onto a plane (constructed from the first threee points) and
    construct a 2D triangulation and finds for the face centres the triangle it
    is in and the weights to the 3 vertices.

    The optional mapMethod nearest will avoid all projection and triangulation
    and just use the value at the nearest vertex.

    Values are interpolated linearly between times.

Usage
    \table
        Property     | Description                | Required    | Default value
        setAverage   | Switch to activate setting of average value | no | false
        perturb      | Perturb points for regular geometries | no | 1e-5
        fieldTableName | Alternative field name to sample | no| this field name
        mapMethod    | Type of mapping            | no | planarInterpolation
        offset       | Offset to mapped values    | no | Zero
    \endtable

    \verbatim
    <patchName>
    {
        type            timeVaryingMappedFixedValue;
    }
    \endverbatim

An example is given in $FOAM_TUTORIALS/incompressible/simpleFoam/pitzDailyExptInlet

Good luck,
Tobi

Thanks For your help Tobias, but who should I enter the (1-(r/d)^2) to my boundary condition?
Is there any possibility to use groovyBC?

[m5m5kh]

No one faced such problem??? any similar experience?
your help is really needed.

Regards,
Mohsen

[Qihao]

Originally Posted by Tobi

Hi all,

in OpenFOAM there is a boundary called timeVaryingMappedFixedValue which can handle tables and makes interpolation inbetween the timesteps. The header file of the class states:

Description
    This boundary conditions interpolates the values from a set of supplied
    points in space and time.

    Supplied data should be specified in constant/boundaryData/\<patchname\>/
      - points             : pointField of locations
      - \<time\>/\<field\> : field of values at time \<time\>

    The default mode of operation (mapMethod planarInterpolation) is to project
    the points onto a plane (constructed from the first threee points) and
    construct a 2D triangulation and finds for the face centres the triangle it
    is in and the weights to the 3 vertices.

    The optional mapMethod nearest will avoid all projection and triangulation
    and just use the value at the nearest vertex.

    Values are interpolated linearly between times.

Usage
    \table
        Property     | Description                | Required    | Default value
        setAverage   | Switch to activate setting of average value | no | false
        perturb      | Perturb points for regular geometries | no | 1e-5
        fieldTableName | Alternative field name to sample | no| this field name
        mapMethod    | Type of mapping            | no | planarInterpolation
        offset       | Offset to mapped values    | no | Zero
    \endtable

    \verbatim
    <patchName>
    {
        type            timeVaryingMappedFixedValue;
    }
    \endverbatim

An example is given in $FOAM_TUTORIALS/incompressible/simpleFoam/pitzDailyExptInlet

Good luck,
Tobi

Hi, can this boundary condition be used as the file which pressure varied with location in x direction, while the time is constant?

[Tobi]

No. The only way is that you make a derivative of that boundary condition and modify it to your needs.

[Taataa]

A while ago I needed a parabolic BC for U and here's the way I did it:

inlet
    {
        type            codedFixedValue;
        value           uniform (0 0 0);
        redirectType    parabolaProfile;   

        code
        #{
            const fvPatch& boundaryPatch = patch();
            const vectorField& Cf = boundaryPatch.Cf();

            vectorField& field = *this; 
            scalar uave = 10;
            scalar h = 5e-3;
            
            scalar vel;

            forAll(Cf, faceI)
            {
                vel = 6 * uave / (h*h) * (h * Cf[faceI].y() - Cf[faceI].y() * Cf[faceI].y());
                field[faceI] = vector(vel, 0, 0);
            }
        #};
    }

Regarding interpolation using tableFile is an option which you can find some info here. I haven't used it myself so you need to explore and let us know if you find any useful info.

Edit: I meant that you can use tableFile inside the code. Since this is a C++ code, you can do all sorts of things without relying on OF classes and functions. You can use C++ capabilities to read from files and do operations though it's more convenient to use OF classes and functions. Also, if you want to include any header you can use codeInclude directive like this:

inlet
    {
        type            codedFixedValue;
        value           uniform (0 0 0);
        redirectType    parabolaProfile;   
        
        codeInclude 
        #{ 
            #include ”someHeaderFile” 
        #}; 

        code
        #{
            const fvPatch& boundaryPatch = patch();
            const vectorField& Cf = boundaryPatch.Cf();

            vectorField& field = *this; 
            scalar uave = 10;
            scalar h = 5e-3;
            
            scalar vel;

            forAll(Cf, faceI)
            {
                vel = 6 * uave / (h*h) * (h * Cf[faceI].y() - Cf[faceI].y() * Cf[faceI].y());
                field[faceI] = vector(vel, 0, 0);
            }
        #};
    }

[Tobi]

The solution you mentioned is working if one has a mathematical formula that can be implemented. If one can do this, it is easy as you demonstrated (by the way there exist a parabolic BC). If one has a table that cannot be fit to a polynomial or other function, one has to modify the varying bc. I guess it is not a big deal or there are already other ways to do it

[Taataa]

Originally Posted by Tobi

The solution you mentioned is working if one has a mathematical formula that can be implemented. If one can do this, it is easy as you demonstrated (by the way there exist a parabolic BC). If one has a table that cannot be fit to a polynomial or other function, one has to modify the varying bc. I guess it is not a big deal or there are already other ways to do it

True. I added some additional points for more clarity.

[gschaider]

Originally Posted by m5m5kh

Dear Foamers

I want to simulate a real blood flow in an aortic aneurysm. I used the paper done by Khanafer et al. entitled "Modeling pulsatile flow in aortic aneurysms:
Effect of non-Newtonian properties of blood"
they used an inlet velocity profile which contains a term of U(t) (please see the attached picture)
Using groovyBC, it is possible to add a parabolic velocity inlet but I don't have any idea how to add a velocity profile term created from interpolation of 350 points. Is there anyone who can help me with this issue?
I will be grateful if you help me with your advice.

Br,
Mohsen

That would work with the "timelines" or "lookuptables" where you can specify a data-file in swak and let it use as a function (or a value that depends on the current time) to be read from a file (with (t,f(t))-pairs). For an example look at Examples/groovyBC/wobbler/0.org/D in the swak4faom-sources