Both NOx and soot emissions are major concerns in compression ignition (CI) engine with diesel fuel and the enhancement of variety of fuel and air can increase the performance of combustion engine. There are several methods to enhance the variety of air-fuel within the cylinder. Altering the geometry of piston bowl is one of the methods to improve the air-fuel mixture. This article proposes the effect of piston bowl geometry on the direct injection diesel engine performance and emissions, where various profiles of piston bowl referred as hemispherical combustion chamber (HCC), toroidal combustion chamber (TCC) and shallow depth combustion chamber (SCC) are designed using computer aided design and drafting (CADD) tool and ANSYS workbench is adopted for analysis. In addition, Karanja oil mixed with base fluid diesel at different volume fractions like0.2%, 0.3% and 0.4% and are calculated for their combination properties. Further, theoretical calculations are considered to determine the properties of Nano fluids which are later used as inputs for the analysis. Finally, CFD analysis is employed on different geometries at different fluid volume fractions and thermal analysis is done for piston bowl geometries with different composite materials like carbon fiber and armide fiber.