Method of calculating radiation

Abstract

Conventionally, a coarse mesh having a same size in that a calculation cell was used regardless to whether the location is near or remote from radiation elements such as calculation cells and wall face elements. Therefore, it took very long calculation time to calculate an energy exchange between a remote location covered by a coarse mesh and a noted cell. Further, there were many non-influential cells for calculation in a location remote from a noted radiation element for radiation calculation, the calculation accuracy was low. The present invention is to propose a method of calculating radiation which is provided with a measure for completing the calculation rapidly while keeping calculation accuracy high. In that, near at a calculation cell from which radiation energy is emitted or at a calculation cell P into which radiation energy is absorbed, a small (level) cell is used and at a remote location from the calculation cell P, a large (level n) cell formed by combining plural small cells is used. Further, a largest calculation cell which comes into field of view angle ΔΩ covered by a ray is selected. As a result, the accuracy of the radiation calculation is enhanced, the calculation time is shortened and amount of memory necessary for the calculation can be reduced.