The damping zone causes a sharp drop in wave height in 3D flume

PPonyPPony
in DualSPHysics v5.0

I created a stationary wave energy device,When I used the three wave elimination methods, the wave height showed a big difference.The water tank is 16m long, 6m wide and 3m deep, and the damping zone is set at the end of 3m long.

<damping>

                <dampingzone>

                    <limitmin x="8.0" y="0.0" z="0.0" />

                    <limitmax x="10.5" y="0.0" z="0.0" />

                    <overlimit value="0.5" />

                    <redumax value="3.0" />

                </dampingzone>

            </damping>

and

<parameters>

            <parameter key="SavePosDouble" value="0" comment="Saves particle position using double precision (default=0)" />

            <parameter key="StepAlgorithm" value="2" comment="Step Algorithm 1:Verlet, 2:Symplectic (default=1)" />

            <parameter key="VerletSteps" value="40" comment="Verlet only: Number of steps to apply Euler timestepping (default=40)" />

            <parameter key="Kernel" value="2" comment="Interaction Kernel 1:Cubic Spline, 2:Wendland (default=2)" />

            <parameter key="ViscoTreatment" value="1" comment="Viscosity formulation 1:Artificial, 2:Laminar+SPS (default=1)" />

            <parameter key="Visco" value="0.01" comment="Viscosity value" /> % Note alpha can depend on the resolution. A value of 0.01 is recommended for near irrotational flows.

            <parameter key="ViscoBoundFactor" value="0" comment="Multiply viscosity value with boundary (default=1)" />

            <parameter key="DensityDT" value="2" comment="Density Diffusion Term 0:None, 1:Molteni, 2:Fourtakas, 3:Fourtakas(full) (default=0)" />

            <parameter key="DensityDTvalue" value="0.1" comment="DDT value (default=0.1)" />

            <parameter key="Shifting" value="0" comment="Shifting mode 0:None, 1:Ignore bound, 2:Ignore fixed, 3:Full (default=0)" />

            <parameter key="ShiftCoef" value="-2.0" comment="Coefficient for shifting computation (default=-2)" />

            <parameter key="ShiftTFS" value="0.0" comment="Threshold to detect free surface. Typically 1.5 for 2D and 2.75 for 3D (default=0)" />

            <parameter key="RigidAlgorithm" value="3" comment="Rigid Algorithm 1:SPH, 2:DEM, 3:CHRONO (default=1)" />

            <parameter key="FtPause" value="0.0" comment="Time to freeze the floatings at simulation start (warmup) (default=0)" units_comment="seconds" />

            <parameter key="CoefDtMin" value="0.05" comment="Coefficient to calculate minimum time step dtmin=coefdtmin*h/speedsound (default=0.05)" />

            <parameter key="#DtIni" value="0.0" comment="Initial time step (default=h/speedsound)" units_comment="seconds" />

            <parameter key="#DtMin" value="0.0" comment="Minimum time step (default=coefdtmin*h/speedsound)" units_comment="seconds" />

            <parameter key="DtAllParticles" value="0" comment="Velocity of particles used to calculate DT. 1:All, 0:Only fluid/floating (default=0)" />

            <parameter key="TimeMax" value="15.0" comment="Time of simulation" units_comment="seconds" />

            <parameter key="TimeOut" value="0.1" comment="Time out data" units_comment="seconds" />

            <parameter key="PartsOutMax" value="1.0" comment="%/100 of fluid particles allowed to be excluded from domain (default=1)" units_comment="decimal" />

            <parameter key="RhopOutMin" value="700" comment="Minimum rhop valid (default=700)" units_comment="kg/m^3" />

            <parameter key="RhopOutMax" value="1300" comment="Maximum rhop valid (default=1300)" units_comment="kg/m^3" />

            <simulationdomain comment="Defines domain of simulation (default=Uses minimum and maximum position of the generated particles)" >

                <posmin x="-20.0" y="-10.0" z="-10.0" comment="e.g.: x=0.5, y=default-1, z=default-10%" />

                <posmax x="20.0" y="10.0" z="10.0"/>

            </simulationdomain>

        </parameters>

1.when I use designphysics to add a damping zone in the flume ,the wave height decreases dramatically,could you help me ?

QQ图片20211203133208.png


2.When I use AWAS, It looks like it's increasing dramatically in the Y direction

QQ图片20211203132259.png


3.The vertical force is obviously much larger than the literature, and there are violent fluctuations in the early stage. How can I avoid it?

QQ图片20211203132824.png


Comments

  • PPonyPPony

    @Alex ,I would appreciate it if you could reply to me

  • PPonyPPony

    I try I'm trying to set the redumax values to 1,3,10,it doesn't work

  • AlexAlex

    You should start first with only a dissipative beach and no device, only wave tank

    After that case you can use damping to reduce the slope...

    Once waves are properly generated, propagated and reflection is avoid with the previous steps, then you can add the device and use AWAS (it is very important to define "startAWAS" just before the first reflected wave (onto the device) will arrive)

    Regards

  • PPonyPPony
    https://forums.dual.sphysics.org/discussion/comment/4779#Comment_4779

    Thank you very much for answering my questions, but I still don't understand…Do you mean there is a problem with my adding steps? When I use design physics, do I follow the steps you said? This simulation is run at one time with set parameters. Can it also be run in parts?

  • AlexAlex

    How you can test if your waves propagate properly using only a dissipative beach if you also use AWAS at the same time?

    I do not understand what you try to do?

    Replying to your questions I was suggestion to run different simulations.. step by step


    Alex

  • PPonyPPony
    https://forums.dual.sphysics.org/discussion/comment/4781#Comment_4781
    • sorry ，I didn't explain clearly，I tried them at different times at the begining：only use damping zone，it causes a sharp drop in wave height in 3D flume；only use AWAS，it looks like it's increasing dramatically in the Y direction.this two methods use vertical wall instead of dissipative beach.Neither of these methods worked until I started using a dissipative beach，the disspative beach works well，but it leads to much particles and more time to simulation.These images compare the results of each of the three methods




  • PPonyPPony
    https://forums.dual.sphysics.org/discussion/comment/4783#Comment_4783
    • I want to replicate the experiment in somebody else's paper, where the wave height is exactly the same as the wave height in the paper when the disspative beach is used,but the damping zone and AWAS work not well


  • PPonyPPony

    @Asalih3d ，What parameters will affect the force in the vertical direction is too large?The peak value of my result is on the high side.What should I do to correctly use the damping zone in a 3D tank?

  • AlexAlex

    Let me clarify and make it easier:

    1) First you run a wave tank with no structure. In this case you will only study wave propagation at the location where structure will be located later, so that you want to be sure that the target wave arrives. In this case you can start with dissipative beach and you can run a 2D simulation to speed up the results. You have to compute wave elevation at the desired location and compare that with reference solution (theory or experimental surface elevation).

    2) Once you are sure that the dissipative beach works ok and that no reflection is generated there, you can move to the case with the structure. If the nature of the experiment is 3D then you have to create your 3D tank. If the structure is creating reflection then you have to use AWAS.

    3) One important issue is the width of the tank that should be minimum 3 times wider than structure width

    4) Another issue is AWAS.. depending on the situation, perhaps only one piston with AWAS working with information at the mid point (in width) of the piston is not enought... then you will have to create sevearl pistons, each one with AWAS


    Regards

  • PPonyPPony
    https://forums.dual.sphysics.org/discussion/comment/4787#Comment_4787

    Thank you very much. I tried to increase the damping zone length to the wavelength, and the attenuation phenomenon is gone. I'll try AWAS again next

Sign In or Register to comment.

© Vanilla Keystone Theme 2024