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The purpose of this paper is to study numerically the fluid flow and heat transfer in an inclined channel provided with heated porous blocks on its lower plate.

The Brinkman‐Forchheimer extended Darcy model with the Boussinesq approximation is adopted for the flow in the porous regions. The governing equations with the appropriate boundary conditions are solved by the control volume method. The effect of some pertinent parameters such as the buoyancy force intensity, the porous blocks shape and height, the porous medium permeability and the Reynolds number are analyzed for various inclination angles ranging from −90° to +90°.

The results reveal, essentially, that the inclination angle of the channel can alter substantially the fluid flow and heat transfer mechanisms, especially at high Richardson and Darcy numbers. In this case, the maximum and minimum global Nusselt numbers are reached for α=+90° and α=−90°, respectively.

The results obtained in this work are valid for an inclined channel with porous blocks attached on the heated parts of the lower plate, whereas the upper wall is thermally insulated.

The results obtained in this worky can be used in the thermal control of electronic components. The use of porous blocks mounted on the heat sources will increase the rate of heat removal in order to maintain the electronic components at an acceptable operating temperature.

The paper provides an interesting method to improve the cooling of electronic devices by use of a porous medium.

The aim is to study numerically the heat transfer enhancement in a double pipe heat exchanger by using porous fins attached at the external wall of the inner cylinder.

The Brinkman‐Forchheimer extended Darcy model is used in the porous regions. The differential equations subjected to the boundary conditions are solved numerically using the finite volume method. Numerical calculations are performed for a wide range of Darcy number (10⁻⁶≤Da≤10⁻¹), porous fins height (0≤H_p≤1) and spacing (0≤L_f≤39) and thermal conductivity ratio (1≤R_k≤100). The effects of these parameters are considered in order to look for the most appropriate properties of the porous fins that allow optimal heat transfer enhancement.

The results obtained show that the insertion of porous fins may alter substantially the flow pattern depending on their permeability, height and spacing. Concerning the heat transfer effect, it is found that the use of porous fins may enhance the heat transfer in comparison to the fluid case and that the rate of improvement depends on their geometrical and thermo‐physical properties. Performance analysis indicated that more net energy gain may be achieved as the thermal conductivity ratio increases especially at high Darcy numbers and heights.

The results obtained in this work are valid for double pipe heat exchangers with the same fluid flowing at the same flow rate in the two ducts and for the case of an inner cylinder of negligible thermal resistance.

The results obtained in this study can be used in the design of heat exchangers.

This study provides an interesting method to improve heat transfer in a double pipe heat exchanger by use of porous fins.

In the present research, a numerical investigation is carried out to study the fluid flow and heat transfer in a double-pipe, counter-flow heat exchanger exploiting metal foam inserts partially in both pipes. The purpose of this study is to achieve the optimal distribution of a fixed volume of metal foam throughout the pipes which provides the maximum heat transfer rate with the minimum pressure drop increase.

The governing equations are solved using the finite volume method. The metal foams are divided into different number of parts and positioned at different locations. The number of metal foam parts, their placements and their volume ratios in each pipe are sought to reach the optimal conditions. The four-piece metal foam with optimized placement and partitioning volume ratios is selected as the best layout. The effects of the permeability of metal foam on the Nusselt number, the performance evaluation criteria (PEC) and the overall heat transfer coefficient are investigated.

It was observed that the heat transfer rate, the overall heat transfer coefficient and the effectiveness of the heat exchanger can be improved as high as 69, 124 and 9 per cent, respectively, while the highest value of PEC is 1.36.

Porous materials are widely used in thermo-fluid systems such as regenerators, heat sinks, solar collectors and heat exchangers.

Having less pressure drop than fully filled heat exchangers, partially filled heat exchangers with partitioned metal foams distributed optimally enhance heat transfer rate more economically.

This study aims to clarify the relationship between inclination angle of hot surface of CPU and its temperature in absence and presence of aluminum foam as a cooling system. It proposes application of the artificial neural [multi-layer perceptron (MLP) and radial basis function] networks and adaptive neuron-fuzzy inference system (ANFIS) to predict interface temperature of central processing unit (CPU)/metal foam heat sink.

To provide a consistent set of data, the surface of an aluminum cone with and without installing Duocel aluminum foam was heated in a natural convection using an electrical resistor. The hot surface temperature was measured using five K-type thermocouples (±0.1°C). To develop the predictive models, ambient temperature, input power and inclination angle are taken as input which varied from 23°C to 32°C, 4 to 20 W and 0° to 90°, respectively. The hot surface temperature is taken as the output.

The results show that in the presence of foam, the hot surface temperature was less sensitive to the variations of angle, and the maximum enhancement of the heat transfer coefficient was 23 per cent at the vertical position. Both MLP network and ANFIS are comparable, but the values predicted by MLP network are in more conformity with the measured values.

The effect of metal foam on the inclination angle/hot surface temperature dependence is identified. The optimum angle is clarified. The applicability of the MLP networks to predict interface temperature of CPU/heat sink is approved.

In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs).

Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers.

For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG.

The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones.

The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.

The purpose of this study is to work on heat transfer enhancement within different engineering cavities is the major aim of most technical solutions. Such intensification can be obtained by using “smart” liquids known as nanoliquids and solid fins. Therefore, free convective thermal transmission within square nanoliquid chamber under the influence of complex fins is studied. The considered fins are the combination of wall-mounted adiabatic fin and an adiabatic block over this fin.

Influences of the Rayleigh number, location of the local adiabatic block and nanoparticles concentration on liquid motion and energy transport are studied. Finite difference technique was used to solve the governing equations.

It has been ascertained that the energy transport intensification can be reached for the middle position of this local block within the cavity.

The main originality of this work is to use intermittent block in a nanofluid filled cavity under differentially heated conditions. One constant and location of one of the passive element is constant and other one is fixed, which is the intermittent block, is used to control heat and fluid flow. Thus, distance between blocks is allowed to control of the velocity and kinetic energy. In this way, temperature distribution also can be controlled inside the square cross-sectional closed space. Another originality of the work is to use nanoparticle added main flow for this geometry. Thus, energy efficiency can be controlled via adiabatic intermittent blocks without spending any extra energy.

This paper aims to discuss about the two-dimensional numerical simulations of fluid flow and heat transfer through high thermal conductivity metal foams filled in a vertical channel using the commercial software ANSYS FLUENT.

The Darcy Extended Forchheirmer model is considered for the metal foam region to evaluate the flow characteristics and the local thermal non-equilibrium heat transfer model is considered for the heat transfer analysis; thus the resulting problem becomes conjugate heat transfer.

Results obtained based on the present simulations are validated with the experimental results available in literature and the agreement was found to be good. Parametric studies reveal that the Nusselt number increases in the presence of porous medium with increasing thickness but the effect because of the change in thermal conductivity was found to be insignificant. The results of heat transfer for the metal foams filled in the vertical channel are compared with the clear channel in terms of Colburn j factor and performance factor.

This paper serves as the current relevance in electronic cooling so as to open up more parametric and optimization studies to develop new class of materials for the enhancement of heat transfer.

The novelty of the present study is to quantify the effect of metal foam thermal conductivity and thickness on the performance of heat transfer and hydrodynamics of the vertical channel for an inlet velocity range of 0.03-3 m/s.

The purpose of this paper is to perform the stimulation in order to examine the effects on the heat transfer coefficient and the flowfield properties at the vicinity of the gap due to variations in the width-to-depth ratio.

The governing equations were discreted by using the finite volume method, and based on pressure-velocity coupled algorithm, the heat transfer coefficients outside and inside the gaps, defined by the width-to-depth ratio of 1, 2/3, 1/2, 1/3 and 1/4, were obtained by the Fluent software.

The number of vortex inside the gap depends on the width-to-depth ratio, and the maximum value of the heat transfer coefficient emerges on the downstream surface.

The study gives a feasible method to simulate the flowfield and the heat transfer inside the gap, which will help the design of the thermal protection system for reentry vehicles.

This study aims to delve into the coupled mixed convective heat transport process within a grooved channel cavity using CuO-water nanofluid and an inclined magnetic field. The cavity undergoes isothermal heating from the bottom, with variations in the positions of heated walls across the grooved channel. The aim is to assess the impact of heater positions on thermal performance and identify the most effective configuration.

Numerical solutions to the evolved transport equations are obtained using a finite volume method-based indigenous solver. The dimensionless parameters of Reynolds number (1 ≤ Re ≤ 500), Richardson number (0.1 ≤ Ri ≤ 100), Hartmann number (0 ≤ Ha ≤ 70) and magnetic field inclination angle (0° ≤ γ ≤ 180°) are considered. The solved variables generate both local and global variables after discretization using the semi-implicit method for pressure linked equations algorithm on nonuniform grids.

The study reveals that optimal heat transfer occurs when the heater is positioned at the right corner of the grooved cavity. Heat transfer augmentation ranges from 0.5% to 168.53% for Re = 50 to 300 compared to the bottom-heated case. The magnetic field’s orientation significantly influences the average heat transfer, initially rising and then declining with increasing inclination angle. Overall, this analysis underscores the effectiveness of heater positions in achieving superior thermal performance in a grooved channel cavity.

This concept can be extended to explore enhanced thermal performance under various thermal boundary conditions, considering wall curvature effects, different geometry orientations and the presence of porous structures, either numerically or experimentally.

The findings are applicable across diverse fields, including biomedical systems, heat exchanging devices, electronic cooling systems, food processing, drying processes, crystallization, mixing processes and beyond.

This work provides a novel exploration of CuO-water nanofluid flow in mixed convection within a grooved channel cavity under the influence of an inclined magnetic field. The influence of different heater positions on thermomagnetic convection in such a cavity has not been extensively investigated before, contributing to the originality and value of this research.

The purpose of this paper is to carry out a numerical study on the dynamic and thermal behavior of a fluid with a constant property and flowing turbulently through a two-dimensional horizontal rectangular channel. The upper surface was put in a constant temperature condition, while the lower one was thermally insulated. Two transverse, solid-type obstacles, having different shapes, i.e. flat rectangular and V-shaped, were inserted into the channel and fixed to the top and bottom walls of the channel, in a periodically staggered manner to force vortices to improve the mixing, and consequently the heat transfer. The flat rectangular obstacle was put in the first position and was placed on the hot top wall of the channel. However, the second V-shaped obstacle was placed on the insulated bottom wall, at an attack angle of 45°; its position was varied to find the optimum configuration for optimal heat transfer.

The fluid is considered Newtonian, incompressible with constant properties. The Reynolds averaged Navier–Stokes equations, along with the standard k-epsilon turbulence model and the energy equation, are used to control the channel flow model. The finite volume method is used to integrate all the equations in two-dimensions; the commercial CFD software FLUENT along with the SIMPLE-algorithm is used for pressure-velocity coupling. Various values of the Reynolds number and obstacle spacing were selected to perform the numerical runs, using air as the working medium.

The channel containing the flat fin and the 45° V-shaped baffle with a large Reynolds number gave higher heat transfer and friction loss than the one with a smaller Reynolds number. Also, short separation distances between obstacles provided higher values of the ratios Nu/Nu₀ and f/f₀ and a larger thermal enhancement factor (TEF) than do larger distances.

This is an original work, as it uses a novel method for the improvement of heat transfer in completely new flow geometry.