Dear WUFI Support team,
I would like to know if the driving rain load that can be estimated with the driving rain coeficients R1 and R2 or with the ASHRAE method must be multiplied by the r.r.f. ("Rain Reduction Factor") in order to get the total amount of driving rain on a vertical surface?
Or is the 0.7 factor (the r.r.f value suggested by the program) only used for capillary absorption related with the moisture model for WUFI?
For instance, to have identical values with the rain gauges for wind-driven rain and the WUFI models should I always use the r.r.f.?
Many thanks for your help.
Regards,
Joao delgado
Rain Reduction Factor
Re: Rain Reduction Factor
Dear Mr. Delgado,
the two driving rain models estimate the amount of driving rain which arrives at the surface.
However, not all of the arriving rain may be available for capillary absorption because some of the arriving rain may splash off when hitting the surface. The r.r.f. accounts for this fact:
amount of water arriving * r.r.f. = amount of water available for absorption
This reduced available amount is then offered to the component for capillary absorption. The component can not take up more water than what is available, that is, even if the component could take up a very large amount of water, due to its capillary properties, the absorbed amount is always limited by what's available.
The r.r.f. has nothing to do with the capillary properties of the component or with the liquid transport model itself.
Regards,
Thomas
the two driving rain models estimate the amount of driving rain which arrives at the surface.
However, not all of the arriving rain may be available for capillary absorption because some of the arriving rain may splash off when hitting the surface. The r.r.f. accounts for this fact:
amount of water arriving * r.r.f. = amount of water available for absorption
This reduced available amount is then offered to the component for capillary absorption. The component can not take up more water than what is available, that is, even if the component could take up a very large amount of water, due to its capillary properties, the absorbed amount is always limited by what's available.
The r.r.f. has nothing to do with the capillary properties of the component or with the liquid transport model itself.
The driving rain models estimate the amount of rain arriving at the surface, and this is also what a driving rain gauge (i.e. a "hole in the wall") would show. But if the rain hits the surface (rather than the hole of the rain gauge), some of it will splash off. So the amount of rain indicated by the models or the rain gauge should be reduced by the r.r.f. to account for the fact that the amount of rain going into a hole is different from the amount of rain remaining on a hard surface.For instance, to have identical values with the rain gauges for wind-driven rain and the WUFI models should I always use the r.r.f.?
Regards,
Thomas