Occasionally when simulating structures that contain insulation, I notice a substantial gap between the brick and insulation layers, as shown in the image below. Could someone kindly explain why that gap is there or what it means?
Screenshot 2023-01-05 at 12.42.15.png (407.49 KiB) Viewed 5261 times
These gaps are also apparent in one of the example cases provided by Fraunhofer IBP (also attached - Example_Exterior wall with interior insulation), but are much smaller:
Screenshot 2023-01-06 at 13.35.41.png (62.08 KiB) Viewed 5261 times
for the numerical calculation, the building component is divided into a grid of discrete grid elements. WUFI calculates the moisture content and the temperature at the center of each grid element. This means that, strictly speaking, moisture content and temperature at other points in the component are unknown.
Within a material layer this is not a problem because it can be assumed with sufficient accuracy that the moisture and temperature profiles are smooth, and in order to display the profiles, the film viewer simply draws straight line segments from one grid element center to the next one.
At the boundary between two material layers, however, there may be a bend or even a discontinuity in the profiles. The profiles could still easily be drawn if moisture and temperature at the material boundary were known. These are not known, however, because the grid is created in such a way that material boundaries coincide with grid element boundaries and not with the grid element centers for which moisture and temperature are known.
Rather than drawing a possibly incorrect shape of the profiles across the material boundary, the film viewer draws a gap which extends from the center of the last grid element of the left-hand material to the center of the first grid element of the right-hand material. The drawn profiles therefore end and begin with known values, between these the film viewer leaves a gap.
The width of the gap depends on the widths of the grid elements adjacent to the material boundary.
