This paper describes interim development of a numerical wave flume for practical use in designing maritime structures. The flume is based on a 2-D numerical wave simulation using a NASA-VOF method particularly selected because it can reproduce highly nonlinear wave profiles against various structures, e. g., impact of a breaking wave on a vertical wall. During fiscal years 1998 to 2000, a cooperative research group has been tasked with this project, having almost completed the associated computer code in 1998 and studied application of the numerical wave flume for practical design of various types of coastal structures.