Increasing Reynolds Number Research Articles

Experimental studies on the effect of Al2O3 + water nanofluid concentrations on dimensionless heat transfer parameters in a cleanroom air handling unit

Nanofluid, a colloidal suspension of nonmetallic or metallic nanoparticles into conventional base fluid and used for heat transfer characteristics enhancement for many industrial applications. Cleanrooms are essential at various industries for controlling airborne contamination and environmental parameters. In this article, heat transfer properties of nanofluid (Al2O3 + water) at various nanoparticle concentrations (1%, 2%, and 3%) on a prototype cleanroom air handling chiller unit was investigated experimentally in laminar flow zone. Thermal conductivity ratio, Nusselt number, Peclet number, and pressure drop were obtained for above nanoparticle concentrations. Experimental investigations indicate the heat transfer properties improvement in a prototype cleanroom air handling chiller unit by using nanoparticle at base fluid. Experimental investigation on varying Al2O3 + water nanofluid concentrations in a cleanroom air handling chiller unit heat exchanger revealed a notable increase in heat transfer by reducing nanoparticle size from 50 to 10 nm and increasing concentration from 1% to 3% volume, resulting in a 17.70% rise in thermal conductivity ratio and a significant 9.23% increase in Nusselt number at higher Peclet numbers. However, this improvement in heat transfer was accompanied by a substantial 72.5% increase in pressure drops, particularly with increased Reynolds number and particle concentration. Manipulating nanoparticle characteristics resulted in substantial improvements in Nusselt number across a wide range of Reynolds numbers, with smaller particle sizes and higher volume concentrations yielding more significant heat transfer improvements. The novelty of this research lies in its investigation of the influence of variable Al2O3 + water nanofluid concentrations, encompassing different nanoparticle sizes, and volume concentrations, on dimensionless heat transfer parameters within a cleanroom air handling unit, offering valuable insights into optimizing heat transfer efficiency in a controlled and critical environment, addressing a significant research gap in the field.

Effects of non-uniform wavy ribs on flow and heat transfer characteristics of turbine blade cooling channel

Aiming at the problem of reduced heat transfer performance and uneven distribution along the ribbed channel in aero-engine turbine blades, the influence mechanism of rib height, rib angle and fillet radius on the flow and heat transfer characteristics of wavy rib cooling channel under different inlet Reynolds numbers is analyzed by experimental and numerical methods. The research illustrates that the non-uniform change of the rib height has the most profound influence on the heat transfer performance of the ribbed channel. Schemes featuring larger initial and final rib heights demonstrate superior heat transfer performance and uniformity, with the friction factor primarily determined by the maximum rib height. The optimal rib height variation scheme shows a 22.6 % increase in overall Nu/Nu0, with only a 6 % reduction in heat transfer evenness. The non-uniform variation of rib angle and fillet radius mainly affects the local heat transfer and friction factor. Increasing Reynolds number, the distribution of friction factor of the large rib height scheme changes more drastically. At a large Reynolds number (Re = 40000), the enhanced heat transfer in the middle and rear sections of the channel due to the larger rib angle and fillet radius comes at the cost of increased pressure loss.

A Note on the Moody Diagram

In this work, we underscore the significance of selecting an appropriate scaling to derive dimensionless quantities that accurately reflect their dimensional counterparts, thereby enhancing the comprehension of the underlying physics. For the loss of head in a pipe flow, we argue that employing inertial force (or kinetic energy) to non-dimensionalized pressure force (or mechanical energy loss) lacks physical justification. As a result, an anomalous trend emerges for the classical friction factor: it decreases as the dimensionless flow rate (Reynolds number) increases, contrary to the behavior observed in the corresponding dimensional quantities. Conversely, by non-dimensionalizing the pressure force with the viscous force, a novel friction factor arises. In laminar flow, it is constant, while in turbulent flow, it is a monotonically increasing function of the Reynolds number, mirroring the behavior observed in the dimensional problem.

Reynolds number effect on the parameters of turbulent flows over open channels

Abstract Experimental investigations were conducted to analyze the effect of Reynolds numbers on turbulent flow properties in a nonuniform sand bed channel. Steady flow simulations were performed over the nonuniform sand bed channel, considering five Reynolds numbers within the range of 36500–53886. This article endeavors to delineate the influence of Reynolds number on turbulent flow properties through meticulous laboratory studies. Observations revealed that higher Reynolds numbers corresponded to increased longitudinal velocity. As the Reynolds number increases by 10 to 47%, various turbulent flow properties exhibit distinct trends. Specifically, the longitudinal velocity, longitudinal turbulent intensity, vertical turbulent intensity, turbulent kinetic energy, Reynolds shear stress, and Taylor scale show increases ranging from 5 to 30%, 15 to 25%, 15 to 20%, 25 to 60%, 20 to 40%, and 35 to 45%, respectively. Taylor scale analysis indicated higher magnitudes associated with higher Reynolds numbers. In-depth examinations of turbulent anisotropy, third-order moments of velocity fluctuations, kurtosis, turbulent kinetic energy production, and dissipation provided additional insights into flow behavior across different Reynolds numbers. This study contributes to a more comprehensive understanding of flow dynamics in nonuniform sand bed channels under varying Reynolds number conditions, bridging the gap between laboratory studies and real-world scenarios.

Enhancing convergence and accuracy: A comparative study of preconditioning for steady, laminar, and high gradient flows over a wide range of Mach numbers

This paper introduces a novel platform that integrates three preconditioning matrices based on conservative variables: the Turkel, Choi–Merkle and Onur matrices. The platform aims to compare these matrices in terms of accuracy and robustness by investigating their performance in solving three distinct and challenging high-gradient laminar flow problems: (i) Bi-Plane NACA0012 airfoil, (ii) lid-driven flow in a square cavity and (iii) flow in a planar T-junction. These problems serve as new and challenging test cases to accurately determine the abilities of the preconditioning matrices. The preconditioning matrices are applied to evaluate the numerical solutions, and their performance in complex flow fields is assessed in terms of accuracy and efficiency. By solving these flow problems, the effectiveness of the preconditioning matrices is thoroughly analyzed. By integrating these preconditioning matrices into a single platform, this paper significantly contributes to the field. The approach enables a direct and meaningful comparison of the performance of the Turkel, Choi–Merkle and Onur matrices in solving these new and challenging laminar flow problems. While all three matrices demonstrate comparable accuracy in predicting flow characteristics like pressure coefficients, Turkel’s method shows superior convergence acceleration across the almost test cases due to alpha parameter and modifications of the momentum equations. In the external flow case, Turkel converges 22–53% faster than the other matrices by adjusting momentum terms with an alpha parameter. For the internal lid-driven cavity case, Turkel again accelerates convergence up to 38% over Choi–Merkle as Reynolds and Mach numbers increase. However, Onur’s method stalls at high Reynolds/Mach numbers. At low values of Reynolds and Mach numbers, Onur reduces computational cost by 17%. Finally, for the T-junction case, Turkel and Choi–Merkle perform almost identically, decreasing CPU time by 55% vs Onur, which lacks convergence robustness. While the preconditioning matrices have similar accuracy, Turkel offers the best convergence improvement by accounting for momentum effects. Onur works well at low Reynolds/Mach numbers but shows limitations at higher values. The selection of the optimal preconditioning matrix should be based on whether momentum or viscosity dominates in the flow field, as well as the intensity of the viscosity gradient rate.

CFD approach to analyze entropy generation, heat transfer of perforated conical ring turbulators embedded in heat exchanger with biological ternary hybrid nanofluid

Perforated conical rings greatly enhance heat transfer by causing flow disruption and increasing fluid mixing. With minimal impact on friction loss, it improves heat transfer by breaking the thermal boundary layer. In this work, entropy generation, overall performance of cylindrical pipe heat exchanger equipped with perforated conical rings are numerically calculated. Shape of the holes is oval and the number of hole are 4. Ternary hybrid nanofluid is the working fluid (coolant). The combination of graphene, Cu and Al2O3 nanomaterials are considered with water as a base fluid. A particular range of Reynolds number is taken into account (5000 − 9000). 50% increase in Nusselt number is noted for using higher volume fraction (0.5%) of ternary hybrid nanofluid. Thermal performance of heat exchanger is increased more than 50%. Entropy generation is higher by using the perforated conical rings. Thermal- hydraulic performance evaluation criteria (THPEC), i.e. ration between Nusselt number and friction factor decreases with increasing Reynolds number which is a promising result. The differences in THPEC of cylindrical tube with and without perforated conical ring (PCR) are highlighted.

Investigation of thermodynamic state evolution, phase transition and mixing of the hydrocarbon droplet in convective supercritical environments

Liquid alkane droplets transit to supercritical fluids under supercritical conditions. However, the subsequent thermodynamic state evolution, phase transition, and mixing in this case, which directly influences combustion in actual diesel engines, need further investigation. We studied the thermodynamic state evolution, phase transition, and mixing of n-heptane droplets in supercritical laminar nitrogen streams through a set of conservation equations. Non-ideal thermodynamic and transport properties were calculated to incorporate the dramatic variation of physical properties in the supercritical regime. We focus on the effects of Reynolds number, ambient pressure, and droplet size on the thermodynamic state evolution, phase transition and mixing of droplets. Results showed that increasing the Reynolds number can accelerate the evolution of thermodynamic states, which leads to the faster transition of droplets from the liquid phase and supercritical fluids to gas-phase mixtures. With the increased Reynolds number, the phase transition rate is increased and the mixing homogeneity is improved due to the enhanced mass transfer. Caused by the negative correlation between mass transfer and ambient pressure, in higher pressure, droplets after the supercritical transition require more time to transition from supercritical fluids to vapor-phase mixtures. Increasing ambient pressure inhibited the droplet phase transition process and deteriorated the mixing homogeneity, but no significant influence was shown on the droplet dynamic evolution process. Smaller droplets transition faster from liquid phase and supercritical fluids to vapor-phase mixtures. The faster thermodynamic state evolution and faster dynamic evolution process of the smaller droplet leads to its more rapid homogeneous mixing with ambient gasses, but the mode of dynamics is independent of the droplet size.

Bifurcation of equilibrium positions for ellipsoidal particles in inertial shear flows between two walls

We conducted a systematic numerical investigation of spherical, prolate and oblate particles in an inertial shear flow between two parallel walls, using smoothed particle hydrodynamics (SPH). It was previously shown that above a critical Reynolds number, spherical particles experience a supercritical pitchfork bifurcation of the equilibrium position in shear flow between two parallel walls, namely that the central equilibrium position becomes unstable, leading to the emergence of two new off-centre stable positions (Fox et al., J. Fluid Mech., vol. 915, 2021). This phenomenon was unexpected given the symmetry of the system. In addition to confirming this finding, we found, surprisingly, that ellipsoidal particles can also return to the centre position from the off-centre positions when the particle Reynolds number is further increased, while spherical particles become unstable under this increased Reynolds number. By utilizing both SPH and the finite element method for flow visualization, we explained the underlining mechanism of this reverse of bifurcation by altered streamwise vorticity and symmetry breaking of pressure. Furthermore, we expanded our investigation to include asymmetric particles, a novel aspect that had not been previously modelled, and we observed similar trends in particle dynamics for both symmetric and asymmetric ellipsoidal particles. While further validation through laboratory experiments is necessary, our research paves the road for development of new focusing and separation methods for shaped particles.

Experimental Investigation of Forced Convection in Plain or Partly Inserted Square Channel with Porous Media

Several techniques are used to improve the channels' heat transfer coefficient and Nusselt number. One of the methods used for these improvements is porous media (PM). This research deals with an experimental study of heat transfer by forced convection inside a square-shaped channel (0.12 x 0.12 m2) with a length of (0.5 m) and a hydraulic diameter of (0.12 m). The heat flux (4791.7 W/m2) is exposed below the test section, and other walls are thermally insulated. The air was used as the working fluid for the Reynolds number range (2689.6 to 5806.3). The channel was partially filled with the PM (glass spheres with 5mm diameter) by taking three different heights layers (20, 40, and 60 mm) and knowing its effect on the temperature distribution, the local heat transfer coefficient, locally Nusselt number, and the average heat transfer coefficient and Nusselt number. Also, the same parameters were studied without PM inside the channel (plain). The results showed that the PM improved the heat transfer coefficient and the Nusselt number. Also, the temperature distribution decreased gradually with the Reynolds number increase for each height layer, the local heat transfer coefficient and local Nusselt number gradually reduced with the length of the test section increase for each Reynolds number, average Nusselt number increased gradually with the growth of the Reynolds number for each height layer. The PM layer at a height of (60 mm) gave the best improvement in the heat transfer coefficient and Nusselt number compared to the other layers. In addition, the friction factor across the test section at this layer decreases gradually with increasing fluid velocity.

Experimental and numerical estimation of wall effect and drag coefficient on hollow frustum settling in annular and non-annular channels

The wall effect and drag coefficient of hollow frustum particles (Tapered hollow cylinders) settling in cylindrical non-annular and annular channels were experimentally investigated. The terminal velocity, V, of the hollow frustum particles is measured by considering flow channels of different diameters filled with various working fluids. The present work deals with the study of drag coefficient for a range of 0.12 ≤ deq/D ≤ 0.44, 0.22 ≤ deq/L ≤ 0.43, and 0.22 ≤ di/do ≤ 0.77. The hollow frustum particle's terminal velocity, V, decreases with increased blockage ratios and di/do ratios. The experiment revealed that the frustum attains a steady-state orientation. The hollow frustum particle is affected by the wall's retardation, which is described by the wall factor. The hollow frustum particle's wall factor (f) depends on the Reynolds number (Re) and blockage ratio. The wall factor increases with increasing Reynolds number up to a certain point called critical Reynolds number, Rec; after that, the wall factor remains constant with increasing Reynolds number. The hollow frustum particles settling in the cylindrical non-annular channel were more subjected to wall effects than those in the annular channel. Simple correlations between the wall factor and the blockage ratio are developed. The current research also focuses on the relationship between Reynolds number (Re) and drag coefficient (CD). The wall effect is considered while estimating the hollow frustum particle's drag coefficient (CD). The numerical estimate of the experimental drag coefficient is made using Ansys- fluent 18.1, and the experimental and numerical results are consistent with each other.

An Analytical Study of Fluid Flow Through a Porous Filled Channel with Permeable Wall: Suction/Injection Wall Conditions

To depict fluid movement in a channel with a rectangle-shaped cross-section and porous walls, the twodimensional Darcy Brinkman equation of motion with uniform suction and injection is analytically solved using the perturbation method. The analytical expressions for non-dimensional axial velocity, normal velocity, skin friction coefficient and pressure drop are obtained using the perturbation method at a low Reynolds number. Graphical analysis has been done for the derived quantities for different Darcy and Reynolds numbers. At higher Reynolds numbers, the emergence of the velocity overshoots and the presence of an unfavourable pressure gradient zone are significantly less noticeable. The streamlines follow the same pattern since the flow is steady. When the Darcy number is large, the non-dimensional stream function expression reduces to the stream function expression available in the literature. Non-dimensional pressure drop increases up to a specific entry length. The skin friction coefficient decreases as the Reynolds number increases. Acceleration of the fluid in the porous region leads to lesser skin friction; hence, pressure drop rises.

Karhunen–Loéve decomposition of high Reynolds number turbulent pipe flows: a Voronoi analysis

We perform the Karhunen–Loéve decomposition of the data from direct numerical simulations pertaining to incompressible turbulent pipe flow at various Reynolds numbers, in order to identify large-scale coherent structures. A novel approach based on the Voronoi diagram is introduced to estimate the energy distribution along the radial direction as a function of the geometrical properties of the modes. In contrast to previous classifications, no user-defined criterion, threshold or ad-hoc separation of the eddies is required since the two most energetic branches are inherently present as the Reynolds number increases. Details about the Voronoi analysis are provided, together with a comprehensive validation and comparison with previous classifications at low Reynolds numbers. We discuss the results and potential of the presented approach at Reτ = 180 and 5200, commenting on the two classes of coherent structures with a varying and constant size in the radial direction appearing at Reτ = 5200.

A zero-net-mass-flux wake stabilization method for blunt bodies via global linear instability

A rectangular cylinder, with an aspect ratio of 5, is a widely used bluff body in engineering practice. It undergoes intricate dynamical behavior in response to minute alterations in the flow angle of attack (α). These modifications invariably precipitate the failure of wake control for classical flow control methods with various α values. In this study, global linear instability, adjoint method, and sensitivity analysis are employed to identify the optimal position for flow control. It is found that the sensitive region gradually transitions from the leeward side to the downwind side of the model as α and Reynolds number (Re) increase. So, we set up airflow orifices for flow control in both positions. Jet flow control on the leeward side effectively inhibits vortex shedding (α ≤ 2°). High-order dynamic mode decomposition is employed to reveal the inherent mechanism of control. Suction control on the downside effectively mitigates the shear layer separation phenomenon induced by the altered spatial structure associated with higher α. A novel zero-net-mass-flux wake control, bionics-based breathe-valve control (BVC), is proposed to optimize the control effect. BVC is applicable for various α and Re, with optimal effectiveness achievable through jet velocity adjustments. The prediction-control approach in this investigation provides a targeted method to mitigate flow-induced vibration.

Laminar Convective Heat Transfer Across a Circular Pipe by using MWCNT + Fe3O4 Hybrid Nanofluid: A Numerical Study

MWCNT + Fe3O4 - water hybrid nanofluid’s heat transfer due to convection through a pipe was studied numerically and presented in this paper. Using the ANSYS FLUENT 22 software, the single phase energy equation of second order, momentum equation, and mass equation are all solved. The diameter of the pipe was 4mm and lthe lengthwas 800mm. Water which was considered the base fluid was used with different volume fractions (0% to t%) of MWCNT + Fe3O4 nanoparticles for a wide variety of Reynolds number (300 to 1000) at a steady heat flux of 2000 W/m2 at the wall of the tubes. The result demonstrates that for both MWCNT + Fe3O4 -H2O nanofluid and water, increasing Reynolds number increases the Surface Nusselt number, skin friction coefficient and also the pressure loss in the evolved region.

Heat transfer characteristics of pulsating flow in a straight channel with rhombic-shaped expanding chamber: A numerical study

ABSTRACT The combination of passive and active heat transfer recovery techniques in channel flows has significant potential in terms of increasing thermal performance. Therefore, this study focused on the numerical examination of the flow and thermal behavior of pulsating flow in a straight duct containing a rhombus chamber. In the context of the study, iterations were solved using the finite volume method (FVM). The study was carried out for different pulsating amplitudes (A: 0.2, 0.4, 0.6, and 0.8), Strouhal numbers (St: 1, 2, 3, 4), and Reynolds numbers (200 ≤ Re ≤ 800). The surfaces other than the adiabatic lengths at the inlet and outlet of the duct were kept constant at Tw = 360 K. Results were compared with the results of the steady flow case. The effects of pulsating velocity and oscillatory parameters on Nusselt number, pressure drop, and performance factor were discussed. Velocity and temperature images were presented for different Reynolds numbers and pulsating components in the channel. The findings revealed that although the pulsating parameters significantly enhanced the heat transfer at increasing Reynolds numbers, they had a fairly low effect on heat transfer at the same Reynolds number. It was observed that at Re = 800, the Nusselt number formed a peak at St = 3 for all tested pulsating amplitudes. For the parameters of Re = 800, A = 0.6, and St = 2, heat transfer and performance factor in pulsating flow increased by 8.96 and 8.22 times, respectively, compared to steady flow conditions.

Enhancing energy efficiency for buildings in hot-desert climate: CFD investigation of Trombe walls using several thermal fins configuration

This study presents a comprehensive computational fluid dynamics (CFD) analysis of Trombe walls in laminar flow conditions, focusing on the impact of thermal fins. The investigation explores configurations with 3 and 5 fins, considering varying fin heights, numbers, and rotation angles. The Nusselt number, friction factor, heat transfer rate, and thermal efficiency are meticulously examined for Reynolds numbers ranging from 600 to 1600. Results reveal that for configurations with three fins, a rotation angle of 70° yields the highest thermal efficiency, showcasing a notable increase from 32.3 % to 44 % across all Reynolds numbers. In contrast, configurations with five fins exhibit enhanced thermal efficiency when fins are maintained horizontally (90°) at low Reynolds numbers but experience a decline as Reynolds numbers increase. Specifically, the thermal efficiency drops from 62.48 % to 55.5 % for Re = 1400 and from 64.7 % to 58 % for Re = 1600. The study concludes that Trombe walls with three fins should be designed with a 70° rotation angle, while those with five fins should feature horizontally oriented fins for optimal thermal performance. These findings offer valuable insights for the design and optimization of Trombe walls, providing guidance for achieving enhanced energy efficiency in passive heating systems.

Thermal stress analysis in pin fin microchannel heat sink

The conjugate heat transfer and the thermal stresses produced within a pin-fin microchannel heat sink are investigated numerically. The pin-fin microchannel heat sink is subjected to a constant heat flux from the bottom surface and cooled by water flow through the channel across the pin fins. Rectangular cross-section microchannel incorporating one raw of square pin fins are considered. The water flowing through the microchannel at Reynolds number varies from 200 to 800. The heat sink dissipates constant heat flux in the range of 75-175 kW/m2. The selected materials used for the solid substrate are Copper, Aluminium, Titanium, and Structural steel. The results are presented as contour plots for the temperature, thermal stress, and deformation distribution. It is found that the heat dissipation and the Nusselt number are increased with increasing Reynolds number, increasing the thermal conductivity of the mate-rial but remain constant throughout various heat fluxes. Thermal stresses are increased with decreasing Reynolds number, increasing heat flux, and increasing Youngs’ Modulus of the substrate material. The total deformation is increased with decreasing Reynolds number, in-creasing heat flux, and increasing the thermal expansion coefficient of the substrate material.

Numerical study of heat transfer in circular pipe filled with porous medium

AbstractForced convection heat transfer was studied in a horizontally heated circular pipe with constant heat flux. Porous medium was created using 1 and 3 mm stainless-steel balls (porosity: 0.3690 and 0.3912). Reynolds numbers ranged from 3,200 to 6,500 based on pipe diameter, with heat flux rates of 6,250 and 12,500 W m−2. ANSYS Fluent simulated a 51.4 mm diameter, 5 mm thick, 304 mm long stainless-steel pipe. Results showed increased turbulence and eddy formation. Analysis revealed higher convective heat transfer coefficient, pressure drop, and Nusselt number with increasing Reynolds number. Nusselt number also increased with 1–3 mm ball diameter. 6% porosity increase reduced pressure drop by 84.4%. Nusselt number rose by 46.7% (Reynolds 3,200–6,500) and 4.36% (heat flux 6,250–12,500 W m−2).

The effects of thermal radiation, thermal conductivity, and variable viscosity on ferrofluid in porous medium under magnetic field

Purpose This study aims to analyze the two-dimensional ferrofluid flow in porous media. The effects of changes in parameters such as permeability parameter, buoyancy parameter, Reynolds and Prandtl numbers, radiation parameter, velocity slip parameter, energy dissipation parameter and viscosity parameter on the velocity and temperature profile are displayed numerically and graphically. Design/methodology/approach By using simplification, nonlinear differential equations are converted into ordinary nonlinear equations. Modeling is done in the Cartesian coordinate system. The finite element method (FEM) and the Akbari-Ganji method (AGM) are used to solve the present problem. The finite element model determines each parameter’s effect on the fluid’s velocity and temperature. Findings The results show that if the viscosity parameter increases, the temperature of the fluid increases, but the velocity of the fluid decreases. As can be seen in the figures, by increasing the permeability parameter, a reduction in velocity and an enhancement in fluid temperature are observed. When the Reynolds number increases, an increase in fluid velocity and temperature is observed. If the speed slip parameter increases, the speed decreases, and as the energy dissipation parameter increases, the temperature also increases. Originality/value When considering factors like thermal conductivity and variable viscosity in this context, they can significantly impact velocity slippage conditions. The primary objective of the present study is to assess the influence of thermal conductivity parameters and variable viscosity within a porous medium on ferrofluid behavior. This particular flow configuration is chosen due to the essential role of ferrofluids and their extensive use in engineering, industry and medicine.

Turbulent mixed convection in a horizontal cylindrical cavity with the off-lattice Boltzmann method

Large-eddy simulations (LES) of turbulent mixed convection in a horizontal concentric cylindrical cavity when cylinders are subjected to rotations are investigated in the present study. A characteristic-based finite-difference off-lattice Boltzmann method solver is employed to investigate whether rotation enhances heat transfer in a horizontal concentric cylindrical cavity configuration where buoyancy acts perpendicular to the cylinder axis. The study focuses on assessing heat transfer characteristics for different rotation intensities in both counter-rotating-cylinders (CRC) and outer-rotating-cylinder (ORC) configurations. The LES simulations are performed for Rayleigh number, Ra=106, and Reynolds numbers, Re=0,500,1000, and 5000 for air (Pr=0.71), employing a classical Smagorinsky sub-grid-scale (SGS) model. The numerical solver is verified using two benchmark problems, namely (i) Buoyancy-driven flow in a differentially heated air-filled cubic enclosure and (ii) turbulent Taylor-Couette flow. The CRC and ORC configurations are chosen for the three-dimensional simulations in this study, prompted by the notable improvement in heat transfer observed in their respective two-dimensional simulations. A thorough comparison between two- and three-dimensional mixed convection results reveals substantial influence from secondary flow in the axial direction. While three-dimensional CRC simulations exhibit a modest increase in heat transfer at Re=500, the ORC configuration experiences a decrease in heat transfer rate as the Reynolds number increases, contrasting with two-dimensional simulation trends. The CRC configuration enhances the axial motion of the flow with Reynolds number, and its magnitude is larger than that of the ORC configuration and natural convection. A significant difference between two-dimensional and three-dimensional mixed convection simulation results is observed because of considerable secondary flow. Furthermore, the flow and thermal characteristics of turbulent mixed convection are investigated using streamlines, isotherms, Q-criterion, Nusselt number variation along the cylinders, anisotropy analysis, turbulent kinetic energy (TKE), dissipation, contours of radial and axial components of velocity.