How does the Gate Valve (TL) block utilize "Cross-sectional area at ports A and B" and "Characteristic longitudinal length"?

I'm building a Simscape Fluids model and am trying to use the Gate Valve (TL) block. One of the inputs is the "Cross-sectional area at ports A and B", but the documentation doesn't say how this is used and it clearly affects the results of the model. Another input, "Characteristic longitudinal length", is described as "Approximate length of the valve. This parameter provides a measure of the longitudinal scale of the valve. The default value is 0.1 m^2." The units in the documentation are incorrect (area vs. length), which isn't comforting, but the equations showing how it is used are again absent. Any help on this would be very appreciated. Thanks.

[Aaron Rimpel]

After playing with the different parameters and reviewing orifice calculations, it appears that the port area is required to define the beta ratio. This description needs to be added to the documentation.

The characteristic length is still a mystery...

Answer 1

[Yifeng Tang]

In the latest version (R2022a), this characteristic length isn't a parameter anymore.

In an earlier version (R2020b), I couldn't find the equation that uses this characteristics length. I guess you also found it to do nothing?

And you are right, the port area is used to calculate the ratio of valve opening area over max port area. It's the S_R/S term below: