1D:Dialog Numerics

Dialog: Numerics

The options offered by this dialog allow you to control the way the calculation is done.

"Mode of Calculation":

"Heat Transport Calculation"

"Moisture Transport Calculation":

Decide whether heat and/or moisture transport shall be allowed in the calculation.

In general, you will have activated both; an example for a case where it is useful to switch off moisture transport is the determination of the heat transmission coefficient (U-value) of a building component with a complicated measured moisture profile: To this end, write the moisture profile to a *.INI file, specify it as the initial moisture content and switch off the moisture transport calculation in the present dialog Numerics to keep the profile from dissolving. Apply a suitable constant temperature difference across the component by creating an appropriate KLI file or by specifying temperature "sine" curves with appropriate mean values and "zero" amplitudes on either side, start the calculation and wait until steady-state conditions have been reached. After the calculation, obtain the heat transmission resistance from the resulting steady heat flow.

"Hygrothermal Special Options":

"Excluding Capillary Conduction":

Capillary conduction can be switched off separately; moisture transport is

then only effected by vapour diffusion. Thus you can examine the contributions

of both transport mechanisms to the total transport.

If the "Moisture Transport Calculation" has been deactivated

altogether, there is of course no capillary conduction anyway, independent

of this option.

 

"Excluding Latent Heat of Evaporation",

"Excluding Latent Heat of Fusion":

If you want to examine the importance of latent heat effects, you can switch

them off and compare calculations with and without latent heat.

 

"Numerical Parameters":

"Increased Accuracy",

"Adapted Convergence":

If a calculation should suffer from numerical problems (recognisable by a

[1D:Dialog_InfoLastCalculationRun | great number of convergence

failures or a bad water balance]]) and a revised [##HREF##] grid can't

solve the problems, you can try to improve the calculation with the help of

these options. In general, increased accuracy is more effective than adapted

convergence. With any of these options computing time increases, of course.

 

Before using these options, you should check if the

numerical grid is well adapted to the problem

at hand. These points are further discussed in the help topic for the

dialog "Status of Last Calculation" and in

"WUFI's performance and limitations".

 

Version notice: the numerical options are enabled only in WUFI Pro.