I apologise for bothering you. I’m studying the drying of walls after a flood and doing simulations, with WUFI 2D, to compare them with the experimental results collected in the lab. I would like to ask you 4 questions (if possible
) . The water vapour transfer coefficient, β, plays an essential role in the drying process, so I’d like to insert it carefully.
The experimental campaign was carried out inside the lab. Therefore I used an indoor boundary condition type to model the laboratory ambiance air (wac. file with the recorded T and RH values).
I know that in WUFI:
β=7×〖10〗^(-9) α convective
And β=7×〖10〗^(-9) min(3.5;α convective indoor side)
Therefore, the smallest value of β we can use is: β=7×〖10〗^(-9)*3.5=2.45*〖10〗^(-8) kg/m^2.s.Pa
1 - Is it possible to decrease this vapour transfer coefficient value? For example, to a value of 2.93*〖10〗^(-9) kg/m^2.s.Pa ?
I thought that, although the walls under study had no coating, I could reduce β by using a small sd value to achieve the desired β value through the following expression:
β'=(δ_a (T))/(S_d+(δ_a (10ºC))/(7×〖10〗^(-9) α convective))
Am I thinking right? In this way, I'll be able to get β values lower than 2.45*〖10〗^(-8) kg/m^2.s.Pa ?
Another question, 2- In WUFI 2D is it possible to get the vapour transfer coefficient, β , along the time as an output result? I know that in WUFI pro it is, but in WUFI 2D I can't find it.
3- β will vary depending on the temperature, but its dependence on airspeed is not considered by the software? (this question is just in case I want to apply an outdoor boundary condition type)
Last question a bit out of place:
4- I read that it was possible to extract the T and RH conditions used as boundary conditions (input) from the Wufigraph results file (just to check). To do this, I thought I had to select a point on the grid corresponding to that boundary condition (usually shown in blue) and ask for the graph. It turns out that when I do this I get a T and RH equal to zero (?).
I really apologise for the long questions!
Thank you very much in advance,
Kind regards,
Teresa
P.s1: I am using is WUFI 2D 4.3.
P.s 2:I attach the questions in word where you can see them better.