In this work entitled "A study of some important Applications of Data Mining Techniques - Numerical Investigation and Performance Evaluation" four types of Data Mining Applications are attempted. The first Data Mining Application is to the phenomenon of salt -finger convection in superposed layers. The physical problem is the onset of finger convection in a porous layer underlying a fluid layer in a gravity modulated environment. The Second Data Mining Application is the implementation of three sequential mining algorithms .More emphasis is laid on PLWAP algorithm which is a version of the...