How to choose a smoothing length. What are the criteria for choosing smoothing length? Is there a test similar to the convergence tests for the smoothing length.

I know that larger the smoothing lengths longer the simulation time. I know that having too large or too small will give unphysical results. But how can we know that a particular value is an optimal/best-fit value for a model?

I know it is a fundamental question, but I don't have a clear idea about this.

Here is an example. I am currently during a sloshing tank simulation and I calculating the pressure at a particular position of the tank. I simulated for multiple smoothing length coefficients (coefh =1, 1.2, 1.5, 1.7, 2) and compared with the experiment. (blue line is the experimental maxima of the peak pressure and the green line is the experimental minima of the peak pressure).

How can I tell with is the best smoothing length value with and without considering experimental results?

Similarly, how to chose an artificial viscosity value? What are the criteria for choosing one?

Thank you

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## Comments

1) H/dp>=10, so that 10 particles in one wave height is a good balance between accuracy and computational time

2) alpha(AV)=0.01

Those results can be found in Altomare et al., 2017

Kind regards

Thank you

BE AWARE - that if you test a lot of different scenarios, you might have to make smoothing length analysis on all of them.

Kind regards

And also in the above plot, the pressure amplitudes did not show any signs of convergence to a particular value but they showed a similar trend.

Kind regards

Same for dp, is it the dp that we vary or the one in constants at the bottom?

swl is the still water level

Alex

"h" the smoothing lenght also appears as "H" in the code,

but in terms of terminology:

- h: smoothing length

- dp: initial particle distance

- H: water height

- hswl: still water level

- d: depth (so similar to hswl in some cases)

- speed of sound is computed, by defaults, as sqrt(g*hwsl)

Alex