[zhangdongjie]

Recently, I was simulating the nozzle with high kn number. Originally, I wanted to write UDF, but I see that some people say that the effect of low pressure boundary slip is very good.

But low pressure boundary slip is like only works in 3D. How can I open this button in 2D?

[pakk]

Make it 3D, with the 3rd dimension very small and symmetry conditions. Then you are basically doing 2D.

[zhangdongjie]

Originally Posted by pakk

Make it 3D, with the 3rd dimension very small and symmetry conditions. Then you are basically doing 2D.

I think I may have made a mistake. In the case of 2D and 3D, "low pressure boundary slip" is available. but when I chose "density based" instead of "pressure based". "Low pressure boundary slip" disappeared again.

[pakk]

Ah, yes indeed. Low pressure boundary slip works only with the pressure-based solver. Anyway, if you are working with low pressures, the pressure-based solver is typically the best choice.

[zhangdongjie]

Originally Posted by pakk

Ah, yes indeed. Low pressure boundary slip works only with the pressure-based solver. Anyway, if you are working with low pressures, the pressure-based solver is typically the best choice.

我模拟的是微型推进器，入口压力1mpa左右，出口速度大概是400m/s。基于压力求解可能不太准确。如果我使用udf的话我不知道温度跳跃的udf要加载在哪里。

[zhangdongjie]

Originally Posted by pakk

Ah, yes indeed. Low pressure boundary slip works only with the pressure-based solver. Anyway, if you are working with low pressures, the pressure-based solver is typically the best choice.

I simulated a micro thruster with an inlet pressure of about 1MPa and an outlet velocity of about 400m / s. Pressure based solutions may not be accurate. If I use UDF, I don't know where the UDF of temperature jump will be loaded.