I provide you with the answers to your question below :

The y+ value is a dimensionless parameter that is used to determine the thickness of the boundary layer in a CFD simulation. A y+ value of 50 is typically used for turbulent flows, while a y+ value of 1 is typically used for laminar flows.

In your case, you are simulating sloshing in a rectangular tank, which is a turbulent flow. However, some literatures have stated that having a y+ value of 1 (laminar) resulted in better accuracy. This is because the sloshing flow in your simulation may be laminar in some regions, such as near the walls of the tank.

If you are concerned about accuracy, you can try running your simulation with both a y+ value of 50 and a y+ value of 1. Then, you can compare the results of the two simulations and see which one produces more accurate results.

Ultimately, the best way to determine the y+ value for your simulation is to experiment and see what works best for your specific case.

Here are some additional things to keep in mind when choosing a y+ value:

• The y+ value should be chosen based on the Reynolds number of the flow. A higher Reynolds number will require a lower y+ value.
• The y+ value should also be chosen based on the type of flow. Turbulent flows typically require a lower y+ value than laminar flows.
• The y+ value should be chosen based on the accuracy that is required. A lower y+ value will result in more accurate results, but it will also require a finer mesh.

I hope this can shed some light on your exp.

Hi Abrirami, well y+1 means you are inside the viscous boundary layer where viscous forces are predominat. Usually, y+1 is raccomanded in order to calculate the velocity gradient correctly without using wall function approach, for instance I suggest to use such approach when dealing with heat transfer or even if you are interested in calculate the wall shear stress