The proposed Modeling is directed to an investigation, designed to manipulate a structure and as a consequent a material properties of alloys, which form during directional solidification. This is accomplished by using a computer simulation, which is based on a new mathematical approach for describing of a dendrite growth process. Electromagnetic effect on a dendrite growth is discussed, and principal relations are suggested. If successfully developed, this capability will provide industry with an additional method of forming a directional structure during a casting process.