Investigation of Brownian Motion of CuO-Water Nanofluid in a Porous Cavity with Internal Heat Generation by Using of LTNE Model

In  this paper,  the effect of  the brownian  term  in natural convection of cuo-water nanofluid  inside a partially filled porous cavity, with internal  heat  generation  has  been  studied.  it  is  assumed  that  the viscosity  and  thermal  conductivity  of  nanofluid  consists of  a  static part and a brownian part of which  is a function of  temperature and the  volume  fraction  of  nanofluid.  because  of  internal  heat generation, the two-equation model is used to separately account for the local solid matrix and nanofluid temperatures. to study the effect of brownian  term various parameters such as  the rayleigh number, volume  fraction  of  nanofluid,  porosity  of  the  porous  matrix,  and conductivity  ratio  of  porous  media  is  examined  and  the  flow  and heat  fields  are  compared  to  the  results  of  non-brownian  solution. the results show that brownian term reduces nanofluid velocity and make  smoother  streamlines and  increasing  the  thermal conductivity leads  to  cooling  of  porous  material  and  achieving  more  nusselt. also  the  greatest  impact  of brownian  term  is  in  low-porosity,  low rayleigh  or  small  thermal  conductivity  of  the  porous  matrix.  in addition, mounting the porous material increases the brownian effect and  heat  transfer  performance  of  nanofluid  but  increasing  porosity up to 0.8 reduces this effect.