SPH Modeling PROBLEM
Hello Everybody,
I am currently trying to model correctly SPH Method with Radioss on a cylinder of 5mm Radius and 20 mm Length. At 10mm which is half the length of Cylinder i made a Membrane of 2 mm Radius Whole. So, basically i want to model correctly SPH Particles of Water which are halfly filled at one side of cylinder and will pass through the membrane to the Other end of the Cylinder. I have model the Contact between Fluid and the Wall of Cylinder by Type-7 Contact with GapMin settings.
So can anybody help me in this Model to correctly Model the Pressure and Velocity of SPH Particles through Inlet and Outlet Boundary Conditions ? Can anyone also help me out in SPH Property setting values like Mp (mass of particle) , Smoothing Length, quadratic Bulk Viscosity and Linear Bulk Viscosity and so on..... I also wanted to know how to model the contact properly because Contact Pressure is very high in My simulation results.
Thanks !
Regards,
Ashish
Answers
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Hi Ashish,
Please search for Smooth Particle Hydrodynamics (SPH) in the Help Menu where the basic aspects of calculating the mass of particles (mp) and smoothing length (h) is described.
Bulk Viscosity (qa) and Linear Bulk Viscosity (qb) values are parameters for defining the viscosity of the fluid. For higher values of qa and qb, the more the viscous behavior of the fluid. Please find this case study: http://www.altairuniversity.com/wp-content/uploads/2015/10/SPH-simulation-animation-for-a-ball-dropped-in-water.pdf
Regarding the SPH inlet outlet conditions (/SPH/INOUT), please find an example file where similar boundary conditions are used: http://www.altairuniversity.com/wp-content/uploads/2012/08/Example_22.pdf and model files are also attached for reference. You can continue with Type 7 contact between the SPH particles and wall.
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Hi George,
Thanks a lot for your reply and your help!
I have modelled SPH-Inlet and Outlet but i dont know why its not working ? I have modelled with Langrangian Elements Type-7 contact. Pressure is not even correct. Can you please guide me what can be the problem in my Model ?
Thanks !
Regards,
Ashish
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Hi George,
Thanks for sending me correction.
Can you please tell what did you do change in the Model ? i cannot find it because ....
I have already run that model and the problem is -> its not showing any Displacement and Velocity values.
Regards,
Ashish
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Hi Ashish,
.The change made was you didn't specify ITYP for SPH-Inlet load collector in your model and ITYP=1 was specified for it. Many penetrations were in the model which were cleared.
In your model, only a constraint (BCS) load collector is there. No other loading conditions are present to create any displacement in the model.
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Hi George,
Thanks that really helps me !
Can you also please tell how to Correctly define Velocity with SPH-Inlet Boundary condition to the Fluid. I have already defined Velocity Curve in my Model if you would have seen ?
But it wonders me why this Velocity Curve is not considered by SPH-Inlet Load Collector ? After Simulation i didn't get any Displacement and Velocity Values even.
Thanks !
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Hi Ashish,
You have to assign the imposed velocity load onto the elements desired. From BC's Manager, create a load collector for imposed velocity and select the elements where the velocity is to be applied.
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Ok Thanks !
But i thought Basic Purpose of SPH-Inlet Load Collector is to define Velocity through it just like in case of CFD to fluid.
Is it not the case ?
Regards,
Ashish
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Hi Ashish,
I will consult and update you regarding this. Meanwhile please go through the help manual on /SPH/INOUT which contains some information regarding this.
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OK ! Thanks George for you help regarding SPH that really helps me a lot.
Regards,
Ashish
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Hi Ashish,
In inlet condition (/SPH/INOUT) there is an option for function identifier for velocity in normal direction. Recall the velocity curve created in that option. The normal vectors should point towards the interior of the domain.
<?xml version="1.0" encoding="UTF-8"?>
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Hi George,
Thanks for suggestion.
I have fixed SPH-Inlet Problem to define Velocity.
But still in my Model Pressure Distribution is not Correct.
It would be really nice if you can chek and let me know what can be the problem.
Thanks !!
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Hi Ashish,
The pressure distribution depends on the velocity function defined. Please make sure that the curve defined is correct.
As per my understanding from the above problem description I made some changes in the model and the model is attached along.Please run the model and check.
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Hi George,
I have fixed my Inlet Problem. Its Working now fine but Outlet is still cant define correctly. Can you please help in that ?
I have attached my model. Please guide me.
Thanks !
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Altair Employee