Use of ComputeForce with multiple structures

GedeGede
in DualSPHysics v5.0

The Measuretool - ComputeForce feature appears to be working for a single structure but not for multiple structures. I would like to use the ComputeForce with measurement at the surface of the structure.

I have some questions regarding the Measuretool - ComputeForce feature in the Dambreak case using DualSPHysics 5.0 as follow:

Question 1. Why we should use the mk number = 20 (-onlymk:20) in line 79 in the “wCaseDambreak_win64_GPU.bat” file (Fig.1) to make the resulting force comparable (see Fig. 2 and Fig. 3) to the experiment result?

In fact, there is no related mk number = 20 (setmkbound mk="20") in the “CaseDambreak_Def.xml” file (Fig. 4), where the existing mk numbers are: 0 (for fluid and box), 1 (for structure), and 10 (for a rectangular area to measure the force).   

I have tried to make a modification by replacing the -onlymk number (in line 79 of Fig. 1) using other mk number, for example, mk number = 10 (-onlymk:10) for reason to match the mk number = 10 (setmkbound mk="10") in line 50 (Fig. 4), but the resulting force that I obtained was incorrect (see Fig. 5 and grey line in Fig. 6). The number of particles (Np) in Fig. 5 is different to Np in Fig. 1. Also, the force in Fig. 5 started with negative values even though the fluids were not yet impacting the structure. I guess that Np here is number of particles of the vertical surface that was set to measure the force. 

Question 2. How to modify the wCaseDambreak_win64_GPU.bat file so that I can get the force measured correctly on the front surfaces of multiple structures?

I have tried to create multiple (four) structures using the Dambreak case (see Fig. 7) and made some modification with the CaseDambreak_Def.xml file (attached) and wCaseDambreak_win64_GPU.bat file (attached) but still failed to get correct results.

Is there anyone here who can help me?

Best Regards,

Gede

Fig 1.png

Fig. 1. Snapshot of wCaseDambreak_win64_GPU.bat


Fig 2.png

Fig. 2. Part of SPH ComputeForce output (mk = 20)


Fig 3.png

Fig. 3. Experiment vs SPH force prediction


Fig 4.png

Fig. 4. Snapshot of CaseDambreak_Def.xml


Fig 5.png

Fig. 5. SPH ComputeForce output (mk = 10)

Fig 6.png

Fig. 6. Experiment vs SPH force prediction

Fig 7.png

Fig. 7. Snapshot of SPH Dambreak model with multiple structures.



Comments

  • Asalih3dAsalih3d

    mk = mkbound + 10

    which is a default rule set in DualSPHysics, with the reason that most of the times one will never simulate more than 10 fluids at a time. Therefore mk's for mkfluid match their number (as far as I remember), but structures (both fixed, moving and floating) need to have +10.

    Kind regards

  • AlexAlex

    Check page 145 of XML_GUIDE_v5.0.pdf (in DualSPHysics_v5.0\doc\guides)


    If you have several structures you should identify them with different mkbound so that you can use those "mk" values to compute force


    Regards

  • GedeGede

    @Asalih3d and @Alex

    Thank you for the information.

    Kind regards.

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