Simulating Water Leakage in a Roof

[Sushmit Shreyans]

I want to model a leak in the roof (conventional roof with asphalt shingles, underlayment and OSB sheathing) to simulate wind driven rain.
For this purpose, I am using an external Moisture Source with multiple leak events (1 hr duration) every alternate day for 3 months.
For experimental testing, we will cut small holes (0.2 sq. in.) through the roof covering and introduce water (X ml. for 1 hour) directly on the surface of sheathing through the hole.

How can I model this in WUFI? I have modeled the roof and use an external moisture input file. But I am not sure if I am translating the amount of water that I actually intend to spray on my roofs correctly in the WUFI model. I want to translate that X ml. of water to Kg/s-m2. Is it right to get the rate by ratio of X ml and area of hole and dividing that by the time for which water is introduced?
Does WUFI consider surface runoff on a sloped roof or it assumes total absorption of water by the surface?

[Manfred Kehrer]

Dear Sushmit,

You should divide you X ml by 1000 to get kg and further divide by 3600 to get kg/s.

If you simulate with WUFI 1D, this water is considered to be shared over the whole area so you already have the value in kg/sm². The area of the small holes are obsolete.

The water uptake of the exterior surface is limited by the water supply (=rain onto the surface) respectively by amount which can be absorbed depending the material properties of the most exterior layer.

All the water which can not be absorbed runs off.

Kind Regards,
Manfred