Influence of temperature dependent conductivity of a nanofluid in a vertical rectangular duct

•Flow and heat transfer in a vertical duct filled with a nanofluid of variable conductivity are analyzed.•Governing equations were discretized using finite difference technique.•The effects of key parameters on the skin friction and heat transfer rate are tabulated.•The results show the essential effect of nanoparticles on flow and heat transfer.

Natural convective heat transfer and fluid flow in a vertical rectangular duct filled with a nanofluid is studied numerically assuming the thermal conductivity to be dependent on the fluid temperature. The transport equations for mass, momentum and energy formulated in dimensionless form are solved numerically using finite difference method. Particular efforts have been focused on the effects of the thermal conductivity variation parameter, Grashof number, Brinkman number, nanoparticles volume fraction, aspect ratio and type of nanoparticles on the fluid flow and heat transfer inside the cavity. It is found that the flow was enhanced for the increase in Grashof number, Brinkman number and aspect ratio for any values of conductivity variation parameter and for regular fluid and nanofluid. The heat transfer rate for regular fluid is less than that for the nanofluid for all governing parameters.