The purpose of this study is to investigate conjugate natural convection inside a partitioned differentially heated square enclosure. A corrugated heat-conducting solid partition of three different values of thickness and three different materials is selected. The partition divides the empty spaces of the enclosure into two fluid zones and those zones are filled with air and water, respectively. The governing Navier-Stokes and energy equations are numerically solved by means of the finite element method. The effects of corrugation amplitude, corrugation frequency, thermal conductivity, position, and thickness of the corrugated solid partition along with the variation of Rayleigh numbers based on the properties of air on thermal and flow fields have been depicted through contour plots of temperature and stream function, respectively. The average Nusselt number along the hot wall and the average temperatures of both air and water in their respective domains have also been examined to observe the influence of the above variations. The change of corrugation amplitude, thermal conductivity, position, and thickness of the corrugated solid partition has considerable effects on heat transfer performance with increasing Rayleigh number. Out of those controlling parameters, it is found that increasing partition thermal conductivity enhances thermal performance by up to 25%. However, the variation of corrugation frequency of the partition as a function of Rayleigh number does not seem to be significant for heat transfer enhancement.

A numerical study of two-dimensional, steady-state pure mixed convection heat transfer of air in a vented square cavity with an isothermally heated rotating cylinder has been performed in the present work. Inflow cold air is imposed through an opening (inlet port) at the bottom of the left wall of the vented cavity, whereas the outflow is induced through an exit port of the same size located at the top of the right wall. The circular cylinder is rotating at a constant angular speed with either clockwise (CW) or counter-clockwise (CCW) direction. The mathematical models of the problem representing Navier-Stokes and energy equations have been solved using Galerkin finite element method. To maintain pure mixed convection, Richardson number is fixed at unity, whereas both Reynolds (Re) and Grashof (Gr) numbers are simultaneously varied within the range of 1 ≤ Re ≤ 500 and 1 ≤ Gr ≤ 2.5×105 respectively. Moreover, the influence of different positions of the rotating cylinder has been investigated through the visualization of streamline and isotherm plots, and the distribution of the average Nusselt number of the cylinder surface. It is found that heat transfer characteristics strongly depend on the governing parameters, the position as well as the direction of rotation of the cylinder inside the vented cavity.

Energy transmission in an efficient mode has become a crucial challenge in both industrial and biomedical systems because of the worldwide energy crisis. An initiative has been taken by the present research for designing energy-efficient industrial and biomedical systems using different fluids. This numerical study focuses on investigating magneto-hydrodynamic conjugate natural convection and entropy generation of a hybrid nanofluid (Ag-MgO/water) in a differentially heated square domain including heat-generating sinusoidal solid partition. The partition is mid-positioned with a finite thickness and divides the computational regime into two flow domains. The FEM has been applied for solving the governing PDEs. The effects of magnetic field intensity and orientation, cavity inclination, heat generation from the partition, and volume fraction of hybrid nanoparticles on temperature distribution, flow field, and local entropy generation have been investigated and displayed by isotherms, streamlines, and isentropic lines, respectively. The contours have been plotted at the highest Rayleigh number for better visualization of thermo-fluid interaction. Considering a wide variation of free convection, thermal performance is determined through the computation of the average Nusselt number along the hot wall, and system energy loss has been evaluated through the calculation of average total entropy generation as well as average Bejan number in both fluid zones. The obtained numerical results show that thermal performance and entropy generation are significantly influenced by the magnetic field intensity and cavity inclination. Thermo-fluid energy transfer is reduced by 11.62% for the highest magnetic field strength whereas the increase of cavity tilting is responsible for a 56.72% decrease in thermal performance. A new regression equation has been derived from the obtained results. The numerical study carried out in this research has superior results compared to the existing methodology and/or experimental/ numerical research.

Interruption of continuous processes and decreasing flow rate over time are very common challenges in peristaltic flow. This research takes an initiative to restrain the thermal and fluid flow rate over time by unsteady finite element analysis of Casson fluid flow through a two-dimensional peristaltic duct. The time-dependent flow equation exists in conjugate forced convection and the energy equation consists of radiative heat flux and entropy reduction. The top and bottom walls of the peristaltic duct are considered as contact with air. A circular bolus is set up in the middle of the duct. Four types of Casson fluids like slurry, silicone oil, apple juice, and blood are used as working fluids. The finite element method of Galerkin’s residual technique is applied to solve the leading second-ordered non-linear partial differential equations with proper border conditions. The effects of pertinent parameters on entropy reduction and thermal transport are analyzed. Results are displayed qualitatively in terms of streamlines, vortex field, and heatline contours as well as quantitatively in the form of average temperature, mean thermal, viscous, and total entropy. The obtained numerical results show that thermal performance and entropy reduction are significantly influenced by forced convection, atmospheric characteristics, internal thermal radiation, and Casson fluids. Approximately 6.99% and 72.13% increment of temperature and flow irreversibility are found for shear stress variation of Casson fluid from thickening to thinning. Decreasing thermal performance of 18.71% and increasing energy loss of 38.07% are noticed within the variation of Casson fluids (slurry, silicone oil, apple juice, and blood). About 14.05% enhancement of thermal transport and 64.91% reduction of total entropy are observed due to increasing internal thermal radiation from 0.5 to 2. The numerical results from this research represent a better thermal and fluid flow rate over time compared to the experimental/existing methodology/numerical research. The obtained flow and thermal transport phenomena expose many attention-grabbing performances which deserve additional investigation on Casson fluid characteristics particularly the continuation of flow rate. A fine approach to the biological peristaltic system is offered by the results.