[yasum]

Hello Everyone,
Please let me know, how can I change the sigma (radiation properties file) value w.r.t. "focal laser radius" and (or) "laser power" because sigma is affecting the minimum and maximum value of melt pool temperature.

I have attached the radiation properties file for reference.

laserDirection constant (0 0 -1);

focalLaserRadius 0.001;

laserPower 2000;

sigma 0.002;

//qualityBeamLaser 1.0;

absorptionEmissionModel localDensityAbsorptionEmission;

Thanks for the previous support and help.

Thanks & Regards
Sumant

[TeresaT]

Hi Sumant

what do you know about this parameter so far?

The laser is implemented as d4sigma and you have to choose an sigma accordingly. However, I am unsure how exactly the laser power is handled outside. If anyone has had a closer look at it, I'd be happy to discuss it.

Regards
Teresa

[Krapf]

Originally Posted by yasum

Hello Everyone,
Please let me know, how can I change the sigma (radiation properties file) value w.r.t. "focal laser radius" and (or) "laser power" because sigma is affecting the minimum and maximum value of melt pool temperature.

I have attached the radiation properties file for reference.



Thanks for the previous support and help.

Thanks & Regards
Sumant

If you want to define the peak laser power you should add "mode GaussianPeak;" and "I0 <peakValue>;" to your radiationProperties file.

Originally Posted by TeresaT

Hi Sumant

what do you know about this parameter so far?

The laser is implemented as d4sigma and you have to choose an sigma accordingly. However, I am unsure how exactly the laser power is handled outside. If anyone has had a closer look at it, I'd be happy to discuss it.

Regards
Teresa

What do you mean with "how the laser power is handled outside"?

[TeresaT]

Outside of the D4Sigma width. Naturally there should still be Laser power with low intensity. However I don't think this is the case here and haven't found it in the code yet. It wasn't a high priority yet.

[Krapf]

Yes, I agree that the power outside of the radius is neglected.
I think this is the relevant file: https://develop.openfoam.com/Develop...RM/laserDTRM.C
In line 245 the for loop is defined:

for (label ri = 0; ri < ndr_; ri++)

ndr_ is the number of segments in radial direction specified by the user. In lines 247 and 249 r1 and r2 are defined:

scalar r1 = SMALL + dr*ri;
scalar r2 = r1 + dr;

dr is the length of the segments in radial direction (line 198):

scalar dr =  focalLaserRadius_/ndr_;

So the last segment starts at r1 = focalLaserRadius_ - dr and ends at r2 = focalLaserRadius_.

[TeresaT]

Thanks a lot, Krapf. I might check how much this in my case really is and see if I can neglect that too or have to adjust it.

[maguro]

Sorry for asking an irrelavant question.
Is there any way to record the ray directions or reflection positions of the laser rays(DTRMparticle)

[TeresaT]

Hi Maguro,

for me it is relevant. I would like to track my particles and their intensity, too. Haven't gotten to it, yet.

I haven't testet it yet, but maybe Langrangian Function Objects might help. Otherwise a look at DTRMParticle.C might give new ideas.

Regards,
Teresa

[Krapf]

If you add

DebugSwitches
{
DTRMCloud 1;
}

to your controlDict you should the see rays/particles. However, I am not sure if the reflected rays can also be seen.

Teresa, this will also print how much power is absorbed. I think you could use this value to check how much energy is lost due to the Gaussian distribution outside of the radius.

If I remember it correctly, it will produce a lot of overhead if the simulation is run in parallel.

[TeresaT]

Thanks again, Krapf, Very useful information. I will try it.

[LucaL]

Hello dear forum,

we also need clarification on the proper use of the LaserDTRM functionality in the icoReactingMultiphaseInterFoam solver.
My students and I would like to use reflection in our model. In this context, LaserDTRM offers Fresnel's recletion. According to the announcement of OpenFOAM (link) the whole thing was also implemented according to the paper of Cho2006, which includes reflections at interfaces and a raytracing approach for the volume of fluid method. To test the whole thing we built a model where a laser emits at 45° onto a wall.

The case runs so far, but according to our expectation the emitted rays (particle in the DTRM cloud) should hit the wall and be reflected in parts under 45° + 90° (Figure 1, origID particle cloud). We have already adjusted various parameters, but the reflection simply does not change at all. The rays remain at their angle of 45° (Fig. 2, Q) and are guided through the material without visible reflection to the other wall.

The DTRM cloud remains at its initial location, also the corresponding flag

DebugSwitches
{
DTRMCloud 1;
}

did not bring any change. We are currently lost and out of ideas - does this work at all as we assume or is there a crucial parameter missing in the model/radiation properties?!

I am very grateful for any help and tips!
Best regards,
Luca


Link to image: https://imgur.com/Yalx6sO

[TeresaT]

Hello Luca,

just a short reply about the debug mode.

Have you tried the debug switch using a normal openFoam installation or a proper debug one?

Regards,
Teresa

[LucaL]

Thanks for the quick reply.

I have tried the whole thing in debug mode - unfortunately no changes. Did it work for you with it???

Greetings,
Luca

[TeresaT]

Hey Luca,

sadly I wasn't able to get the debug version going due to time issues. I hope to be able to do this next week. If so, I will tell you about it.

[yasum]

Hello Friends,
How to define temperature dependent thermal conductivity in laser simulation by using "icoReactingMultiphaseInterFoam" solver. Kindly suggest to me or share any related documentation. I would love to appreciate your kind help.

Thanks & Regards

[Krapf]

If you replace "constIso" in thermophysicalProperties.* with "banana" (or any other arbitrary word) and run icoReactingMultiphaseInterFoam, you'll get an error message with the valid options for defining the thermal conductivity.

[maguro]

Hello fellows,
With reviewing the codes in laserDTRM files, I found a problem.
Here is the code that writing for adding a new reflecting beam in function bool Foam:TRMParticle::move, if I'm not wrong.

                    if (cellI > -1)
                    {
                        DTRMParticle* pPtr = new DTRMParticle
                        (
                            mesh(),
                            insertP,
                            insertP + newDir*mesh().bounds().mag(),
                            I_*rho,
                            cellI,
                            dA_,
                            -1
                        );

                        // Add to cloud
                        spc.addParticle(pPtr);
                    }

And it is called from laserDTRM.C by

   
 DTRMParticle::trackingData td
    (
        DTRMCloud_,
        aInterp,
        eInterp,
        EInterp,
        TInterp,
        nHatInterp,
        reflectingCells,
        reflectionUPtr,
        Q_
    );

    Info<< "Move particles..."
        << returnReduce(DTRMCloud_.size(), sumOp<label>()) << endl;

    DTRMCloud_.move(DTRMCloud_, td, mesh_.time().deltaTValue());

But it seems that even if there are particles added at the end of the list(trackingData), the new reflecting particles are not being calculated. (I have exported the particles' ID, direction, position to see what happened.) Any ideas for fixing this problem?

[TeresaT]

Hey Magura,

could you please share how you exported the particles parameters?
I have no idea how to fix that yet.

Regards
Teresa

[TeresaT]

Hi all,

has anyone simulated multiple lasers yet? Is it possible to add multiple laser instead of just one using laserdtrm?

Regards,
Teresa

[Dhar]

Dear Foamer ,

How we can put latent heat of fusion and vapourization as an input in solver "icoreactingmultiphaseinterfoam" for SLM simulation? , Is it feasible to put in solver?

I welcome your suggestion in this regard.