چكيده به لاتين
At the current project, nanofluid natural convection studied in two dimensional porous cavity for heat transfer improvement by lattice Boltzmann method. In this regard, at first LBM and its approach to fluid mechanism and heat transfer problems investigated. This method which has advantages in two-phase and porous media due to its mesoscopic approach than other CFD methods, developed as parallel FORTRAN code for two-phase fluid-fluid and fluid-nanoparticle simulation. Equations and simulation procedure with this method described and investigated. After full acquaintance with LBM, numerical code developed for different problems simulation such as natural convection in porous media or under magnetic field effect for nanofluid with different concentrations and inter-particle forces in various geometries. Each phenomena investigated as practical problem where in all these studies, nanofluid and its effects on heat transfer and fluid flow considered as a main subject. For better analyzing, numerical code investigated from first and second law of thermodynamic points to find best heat transfer and fluid flow conditions. Results showed that, magnetic instability in Hartmann range 0 to 20 happens in 〖10〗^4 Rayleigh value which has high importance. Also Cu/water nanofluid in most researches has positive effect on heat transfer but in current study, nanofluid use as the same time with nanofluid also shows negative effects in different situations. In current investigations, thermal conductivity of porous media has different effect on heat transfer in various Ra values and also in some cases porous media using shows improvement in fluid circulation than without porous media.