Heatlines visualisation of mixed convection flow in a wavy heated cavity filled with nanofluids and having an inner solid block

•Mixed convection and heatlines visualization of nanofluid in wavy enclosures including inner solid block is determined.•Finite element method was employed to solve the dimensionless governing equations in 2D weak formulations.•Comparisons among experimental/numerical data are accomplished concerning the validity of the existing code.•Impacts of number of oscillation and inner block length on the rate of heat transfer are established.