You can use FlowMaster to calculate the efficiency of your On Grade inlet. See the screenshot below for reference;
However, you would have to specify certain grate parameters such as grate width, length, type and clogging factor (%). The grate types available for selection are as per HEC-22 (3rd Edition) Design Manual on Urban Drainage. See the link to the manual here.
In FlowMaster you can then compute "efficiency" for the grate parameters provided.
Let me know if this helps.
Bentley Technical Support
thank you for the reply,
yes, I have seen video of finding out efficiency using Bentley flowmaster, but I have one query regarding it, grate type is limited to certain inlets only,
I have made inlet with opening of 20° from vertical, there are no such inlets that matches this, even this inlet is having 15nos of openings in it and also made of steel.
If it is possible to add such inlet type and by changing the dimensions, I may get the optimum results.
let me know about it.
As I have stated in my response below, you would have to choose the grate type as per the HEC-22 manual. Go through it (from the link I shared) and see which grate type needs to be used. You would also need to calculate the clogging factor (%) manually by counting the void spaces due to the slots to use it to calculate the efficiency.
Yes, I have gone through it, thete is no such grate that has 20° inclination,
In HEC-22 manual it starts with 30° inclination.
Is there any other way to for the result?
If you have information on the expected capture efficiency or the capture amount for a given inflow, you could use one of the other inlet types instead.
The grate types are the only ones available in StormCAD at this time. You may be able to get away with using another grate type to estimate the capture for a given grate.