Air Layer Problems

[majid azadeh]

I am new to this forum, so please bear with me if you've had an inquiry about this issue in the past.

I am modeling a cavity wall assembly with cases that include batt insulation, and air layer (when the insulation was found to be missing). When I try to run the second case (air layer instead of batt), I receive the following error message:

Material: Air Layer 70mm
Material Function: Thermal conductivity, moisture-dependent. water content greater than allowed (see porosity)..

any ideas what the issue maybe. i get the same error message when modeling air layer with or without additional moisture capacity.

Thanks.

[Thomas]

I receive the following error message:

Material: Air Layer 70mm
Material Function: Thermal conductivity, moisture-dependent. water content greater than allowed (see porosity)..

Hi Majid,

this is an error in the material database. It has been corrected in the last WUFI update (see the update of May 12, 2010 on our update page). Please download the current WUFI version from our downloads page and install it using your existing license code (if you have a commercial license code, this will install the full version, even though the download says 'WUFI light').

Kind regards,
Thomas

[majid azadeh]

Thank you for your assistance.

[majid azadeh]

Thomas,

I just got around to looking at what version I am running. I am running Pro 5.0 Version 5.0.2.527.DB.24.68. The updates you recommended were for Version 5.0.2.527.DB.24.67.

Thanks.

[Thomas]

I am running Pro 5.0 Version 5.0.2.527.DB.24.68.

Hm, this database version should have the corrected air layers. If you still see the porosity-related problems, i can only guess that maybe you updated from an earlier version and for some reason updating the database didn't work properly, or maybe you have manually changed some data, unwittingly creating an inconsistency.

All the air layers 'without additional moisture capacity' should have a porosity of 0.001 and a moisture storage function consisting of the two lines

RH [-] -- Water content [kg/m³]
0.0 -- 0.0
1.0 -- 0.017

The other air layers should have a porosity of 0.999 and a moisture storage function consisting only of the single line

0.0 -- 0.0,

indicating that the program's default moisture storage function shall be used.

If a material has a tabulated moisture storage function whose 'free saturation' (i.e. the water content for RH = 1) is greater than the maximum water content (i.e. the porosity multiplied by the density of water, 1000 kg/m³), then WUFI will react with the error message you saw.
For example, a material with a free saturation of 210 kg/m³ (this number is taken from a sandstone) must have a porosity greater than 0.21, so that the maximum water content is greater than 210 kg/m³.

Regards,
Thomas

[ADavis]

I am having the same problem.
I have checked the values in the database, and the problem persists. Is there another workaround?

Thanks!
A