modelling

Describes a fluid flow modelling technique in which the Navier Stokes Equations are replaced by a method which follows the movement of particles. The particles interact according to the Newtonian law of Conservation of Momentum. This technique is made possible by the use of parallel central processing units to replace the normal serial computer. Two such processors are described. The first, developed at Princeton University, is capable of undertaking 20 million cell updates each second. The second is capable of 10 to the power of 9 updates each second.

The objective of this paper is to present validated mathematical models for estimation of hourly and daily solar irradiation on surfaces of arbitrary orientation and tilt from irradiation on a horizontal plane. Daily irradiation on a surface may still be estimated even if only the hours of sunshine are known. To do this regression equations have been established to estimate the hourly or daily diffuse irradiation, given the corresponding horizontal global irradiation.

Long term measurements of attic wood moisture content have shown that at least fifty kilograms of water may be stored in roof sheathing members over the course of the winter, to be released in the spring. Overlaid on this seasonal cycle there is a daily variation driven by temperature changes in the attic. A dynamic model is required to predict the resulting attic air humidity ratio. Hourly moisture flows in a typical attic - from ventilation and from the wood - are examined, and a simple first-principles dynamic mathematical model to relate them is developed.