Common Flow Down Research Articles

Research on heat transfer augment of the helical half-pipe jacket by jet longitudinal vortex generator

In order to evaluate the comprehensive performance of enhanced heat transfer by jet more reasonably, considering the increase of additional power consumption caused by jet, the thermal coefficient ratio (TCR) was proposed as the evaluation index to analyze the effect of comprehensive enhanced heat transfer. In this study, the jet vortex generator (JVG) is applied to the half-pipe jacket for obtaining further heat transfer enhancement. The structural parameters of the half-pipe jacket is kept constant. The effect of the jet incidence angle (α) and the ratio of jet flow rate to mainstream flow rate (ε) on the heat transfer augment has been investigated by numerical simulation. The results showed that the jet action changed the original secondary vortex structure and enhanced the convective heat transfer capacity of the fluid in the helical half-pipe jacket. In the flow region near the jet, a pair of common-flow-down (CFD) longitudinal vortices were generated in the cross section of the half-pipe jacket. With the development of the mainstream, the vortex gradually evolved into a common-flow-up (CFU) vortex. With the increase of ε, heat transfer convective heat transfer capacity was enhanced. Moreover the flow resistance was increased. The local Nusselt number (Nulocal) of the heated wall could be enhanced by up to 2.3 times in the investigated range when compared to the corresponding value of the single half-pipe jacket. Within the range of ε=0.5-2 and α=45°-60°, the jet with α=50° had the best comprehensive enhanced heat transfer performance. The TCR was between 0.91 and 1.19.

Experimental investigation of heat transfer enhancement and pressure drop of fin-and-circular tube heat exchangers with modified rectangular winglet vortex generator

The presence of vortices in a flow field significantly impacts heat transmission. The effect of a modified rectangular winglet vortex generator on heat transfer and pressure drop performance for a fin-tube heat exchanger (FTHE) is experimentally explored in this work. Design and fabrication of full-scale prototype of an FTHE are carried out. Two types of rectangular winglet vortex generators (RWVGs), i.e., Flat RWVG and RWVG with a circular punched hole are installed into the FTHE for experimentation purposes. The experimental studies are conducted with Reynolds numbers ranging from 8000 to 25,000. The experimental results show that the use of RWVG in FTHE provided a much greater heat transfer coefficient than FTHE without RWVGs with an increase in pressure loss penalty. For better wake management, the RWVG are installed behind the circular tubes in a common flow down (CFD) arrangement. The comparative study is carried out to explore thermo-fluid performance of fin-and-tube heat exchanger with two inline circular tube arrangements for all considered cases of RWVGs. By varying the tube wall temperature (i.e., 65, 75, and 85 °C), thermo-hydraulic performance criteria such as Nusselt number (Nu), friction factor (f), and thermal performance factor (η) are compared. Lower tube surface temperature gave the highest enhancement in heat transfer performance with a lower friction factor. However, the thermal performance factor (η) for the RWVG with a circular punched hole is about 1.04–3.2%, 1.3–5.4% and 2.3–10.52% higher than RWVG-Flat for the tube wall temperature 65 °C, 75 °C, and 85 °C, respectively.

Enhancement in Film Cooling Effectiveness Using Delta Winglet Pair

Abstract A simulation study has been carried out to investigate the influence of delta winglet pair (DWP) for improving the film cooling effectiveness of a gas turbine blade. Incompressible continuity, momentum, energy, and two equations k − ω SST model have been used for investigating the nature of flow field, temperature field, and turbulent statistics. The Reynolds number based on the jet velocity and the diameter of the film cooling hole is set at a constant value equal to 4232. The jet to the crossflow blowing ratio has been varied as 0.5, 1.0, and 1.5. The corresponding Reynolds numbers based on the crossflow inlet velocity and film hole diameter are equal to 6462, 4229, and 3231, respectively. It is observed that common-flow-down (CFD) DWP configuration augments the film cooling effectiveness due to generation of secondary longitudinal vortices, which annihilates the counter-rotating vortex structures present in the baseline flow. The generation of hairpin vortices and the growth of shear layer vortices are modified due to the implementation of DWP. The overall turbulence intensity and vorticity get reduced due to the presence of DWP. A maximum of 97.46% and a minimum of 61.50% enhancement in film cooling effectiveness have been observed at blowing ratio of M = 1.5 and M = 0.5, respectively. The wake region of the film cooling jet is modified due to DWP leading to formation of stagnation region and lower mixing resulting in higher film cooling effectiveness. The strength of horseshoe vortices is reduced due to the presence of DWP, resulting in lower mixing between the jet with the cross flows and stable film formation. Lower thermal boundary layer thickness is observed in DWP configuration compared to that of the baseline case confirming lower mixing due to the implementation of DWP. Overall, the present study explains the effectiveness of DWP configuration for enhancement of film cooling effectiveness of a DWP.

Efek vortex generators terhadap peningkatan perpindahan panas pada aliran melewati heated tubes

In this decade, improving the rate of heat transfer has become a big challenge. The high thermal resistance of the gas side of the heat exchanger has an impact on the low rate of heat transfer. Therefore, an experimental study was carried out aimed at looking at conditions of hot temperature and decreased air flow pressure through a heated tube in a rectangular channel using artificial surfaces, namely the concave delta winglet and delta winglet vortex generators. Concave delta winglet vortex generators (CDW VGs) are installed in-line and staggered with one, and two pairs are arranged in common-flow-down (CFD) in the direction of flow with an angle of attack of 15o. The experimental results show that the best thermal performance is observed in the use of two rows CDW VGs staggered, where the value of performance evaluation criteria (PEC) is 28.88% higher than the use of CDW VGs in-line, DW VGs staggered and DW VGs in-line at the same Reynolds number. At the same Reynolds number, the Nusselt number ratio and the friction factor ratio increased 45.25% and 152.05% respectively, occurring in two rows of CDW VGs staggered compared to other vortex generators.Keywords: vortex generators, heat transfer, Nusselt number, friction factor, PEC

An experimental comparison of delta winglet and novel type vortex generators for heat transfer enhancement in a rectangular channel and flow visualization with stereoscopic PIV

Vortex generators (VGs) make a very important contribution to enhancement of heat transfer in many applications. In this study, the comparison of a novel type of vortex generator (NTVG) producing longitudinal vortex (LV) with delta winglet pair (DWP) in terms of improving heat transfer was investigated experimentally. VGs were placed on the bottom surface of the rectangular channel. In order to make a correct comparison, projected areas of each vortex generator were kept equal. The position of the DWP, which ensured that the thermal enhancement factor (TEF) was maximal, was determined from the literature and placed (CFU, common flow up) accordingly on the bottom surface of the channel. As a result of the experiments, the highest TEF for DWP was obtained at about 1.15 and the results were found to be compatible with the literature. The highest TEF value for the NTVG was obtained of about 1.34. Consequently, enhancement in the heat transfer by NTVG was obtained higher than that of DWP. The transverse pitch ratio, Pt (=P/W) where the highest thermal enhancement was provided, was determined for the NTVG. When the transverse pitch ratio Pt was 0.4, the highest TEF value was obtained. LVs generated by the NTVG were visualized by using the PIV (Particle Image Velocimetry) system. The single NTVG has capacity to be able to produce two longitudinal vortices. It was seen that CFD (common flow down) and CFU, flow arrangements were generated at the back of VG and between VGs, respectively. According to the experimental results obtained, we can suggest that using NTVG instead of DWP is more effective in improving heat transfer.

Thermal performance augmentation of fin-and-tube heat exchanger using rectangular winglet vortex generators having circular punched holes

In fin-and-tube heat exchangers (FTHEs), vortex generation is found as one of the promising emerging passive technique for augmenting the rate of heat transfer on air-side. In the present study, three dimensional numerical study is performed to evaluate thermo-hydraulic performance of FTHEs equipped with rectangular winglet vortex generators (RWVGs) with circular punched holes for Reynolds number varying from 400 to 2000. Various cases of RWVGs without and with circular punched holes (1, 2, 4, and 6 holes) are considered. The pairs of RWVG are placed in common flow down (CFD) orientation behind the circular tubes to improve wake management. The effect of number of punched holes is compared with non-VG baseline case and RWVG without hole for flow structure and thermo-hydraulic performance of FTHE with four inline circular tube arrangement. Comparison is also carried out with thermo-hydraulic performance criterions which include Nusselt number (Nu), Pressure drop (ΔP), friction factor (f), colburn factor (j), London area goodness factor (j/f). Effects of number of punched hole on the performance of RWVGs is also evaluated using dimensionless number (j/j0)/(f/f0) as performance evaluation criteria (PEC) . It is observed that RWVGs with circular punched holes remarkably improve the thermo-hydraulic performance of FTHE. The punched holes exhibit reduction in the flow resistance for all cases with slight reduction in Nusselt number. RWVG with 6 holes shows better performance as compared to other cases. Nusselt number for RWVG with 6 holes increases about 45.95% and 57.37% at Reynolds number 400 and 2000, respectively. However, friction factor is decreased by about 13.81%. Thus, from the point of view of London area goodness factor, RWVG with 6 holes found better than other considered cases of RWVG.

Numerical investigation of laminar flow and heat transfer in a channel using combined nanofluids and novel longitudinal vortex generators

Enhancement of heat transfer in plate-fin heat exchangers can be obtained using vortex generators (VG). The three-dimensional laminar flow of water/Al2O3 nanofluid with different nanoparticle volume fractions in a channel with longitudinal vortex generators is numerically simulated. Two novel forms of modified delta winglet VG pairs (MDWP1, MDWP2) are introduced by adding and subtracting a part of the quadrant profile to the delta winglet VG profile. Simulation is carried out for the classic delta winglet pair (DWP) and MDWPs. Performance of heat transfer and pressure drop is compared as well as the overall performance analysis of channel is conducted for all three forms of VGs and two flow arrangement types, common flow up (CFU) and common flow down (CFD). Analytical expressions from the literature are used to check the validity of the model. Governing equations of laminar fluid flow and heat transfer are solved based on the finite-element method. The range of Reynolds number is from 100 to 500. Results show that in the range of the present study, using nanofluid increases about 20% of the heat transfer coefficient and 18% of pressure drop compared to pure water. As results confirm in all of the cases, the heat transfer coefficient increases using VG. The MDWP2 leads to the highest pressure drop and heat transfer between the three VGs types. It can produce up to 9% higher heat transfer coefficient in Re = 100 and 20% of higher pressure drop for CFD flow arrangement. The overall performance of the CFD arrangement is higher than CFU for the studied cases relatively. And the values of performance in a channel with DWP are greater than MDWP1 and MDWP2, which is due to the lower pressure drop of DWP.

Characteristics of Flow Symmetry and Heat Transfer of Winglet Pair in Common Flow Down Configuration

The effect of transverse pitch between a pair of delta-winglet vortex generators arranged in a common flow down configuration on the symmetrical flow structure and heat-transfer performance was numerically investigated. The results showed that symmetrical longitudinal vortices form a common flow down region between the vortices. The fluid is induced to flow from the top towards the bottom of the channel in the common flow region, which is advantageous to the heat transfer of the bottom fin. The vortex interaction increases and the vortex intensity decreases along with the decrease in transverse pitch of vortex generators. Vortex interaction has a slight influence on pressure penalty. The Nusselt number decreases with increasing vortex interaction. The vortices gradually attenuate and depart from each other during the process of flowing downward. A reasonable transverse pitch of delta-winglet vortex generators in a common-flow-down configuration is recommended for high thermal performance.

Comparative study of heat transfer enhancement and pressure drop for fin-and-circular tube compact heat exchangers with sinusoidal wavy and elliptical curved rectangular winglet vortex generator

Vortex generation has emerged as a promising passive method for enhancing air-side heat transfer. In the present work, two-dimensional numerical analysis is carried out to examine the thermo-fluid analysis of fin-and-tube compact heat exchangers with sinusoidal wavy and elliptical curved type rectangular winglet vortex generator (RWVG) having varying Reynolds number ranges from 400 to 1000. The wavy and curved VGs are also placed as up and down configurations with respect to flow direction. Thus the effect of the different common flow down (CFD) configurations of wavy-up, wavy-down, curved-up, curved-down and flat rectangular winglet is compared with baseline configuration (non-winglet case) for flow structure, temperature distribution and pressure distribution for fin-and-tube compact heat exchanger with seven inline circular tube arrangement. They are also compared with thermo-hydraulic performance criterions which include Nusselt number (Nu), Pressure drop (ΔP), friction factor (f), London area goodness factor (j/f). Appreciable improvement in heat transfer characteristics is observed with wavy and curved rectangular winglet with a moderate loss in pressure. Compared with the non-winglet baseline and flat RWVG case, the heat transfer performance of the fin-and-tube heat exchanger is significantly improved with wavy-up and down and curved-up and down configurations. Further, it is also noted that up-wavy RWVG showed the best heat transfer improvement compared to any other RWVG configuration considered. However, Wavy-up configuration has the lowest values of j/f than others and curved-down has higher values of j/f than others. Thus, curved-down RWVG found suitable than other cases of RWVG as far as London goodness factor strategy.

Enhancement of thermal and hydraulic performance of compact finned-tube heat exchanger using vortex generators (VGs): A parametric study

In this study, a numerical analysis is conducted to investigate the influence of interrupted surfaces on compact heat exchangers (CHXs). The performance of CHXs in terms of heat transfer enhancement and pressure drop can be augmented by incorporating innovative passive techniques. In relation to that the influence of delta winglet vortex generators (DWVGs) on thermal-hydraulic features of heat exchanger is elucidated. The effect of vortex generators (VGs) with different number of rows (N), attack angles (θ) and configuration on heat transfer performance (j) and pressure drop (f) are demonstrated. Moreover, the influence of tube arrangements such as inline and staggered placement of tubes and different tube shape (circular, oval and rectangular) are also deduced. The optimum attack angle (θop) of VGs is concluded i.e. 1650, which provides higher transfer performance at moderate pressured drop (ΔP). Array of winglet rows gives comparatively higher heat transfer rate than one row of winglets and also common flow down (CFD) configuration of winglets are preferable over common flow up (CFU) configuration of winglets. Moreover, staggered tubes arrangement tends to provide relatively better thermodynamic features as compared to inline arrangement of tubes. Finally, it is concluded that oval and circular tubes deliver quite comparative act in terms of thermal and hydraulic performance as compared to rectangular tubes.

Parametric study of major factors affecting heat transfer enhancement in a circular tube with vortex generator pairs

This paper deals with the parametric study of major factors influencing thermal and flow behaviors for delta winglet vortex generator (DWVG) pairs in a circular tube. The investigated parameters include six pitch ratios (PR = P/D = 2.4, 3.6, 4.8, 6.4, 9.6, and 19.2), two flow directions (upstream and downstream), and two winglet configurations (common-flow-down (CFD) and common-flow-up (CFU)). The air-flow and heat transfer behaviors in the tube are examined for Reynolds number Re = 5 × 103–2.5 × 104.The experimental results indicate that PR has a significant effect on the heat transfer enhancement. A smaller PR results in a higher Nusselt number and a higher friction factor. The PR = 9.6, corresponding to two winglet rings, yields the largest thermal enhancement factor (TEF) for the Re range examined. The combinations of winglet configuration, flow direction and angle of attack lead to the best TEF performance for α30°-s15-h7.5, α20°-s15-h7.5, and α30°-s20-h10 where α, s and h represent the angle of attack, spacing between VGs and height, respectively. As to winglet configuration, CFD configuration yields better thermal-hydraulic performance than CFU. Furthermore, the downstream flow renders 30–33% higher TEF than the upstream flow.

Thermal and hydraulic characteristics of trapezoidal winglet across fin-and-tube heat exchanger (FTHE)

Heat transfer augmentation by using vortex generator (VG) as an enhancement method in plain fin-and-tube heat exchanger (FTHE) has recently captured high attention of many researchers. In the present study, the flow characteristics and thermal performance across the FTHE with and without trapezoidal winglet vortex generator (TWVG) are investigated using dye injection technique by experimental approach and numerical simulation using finite volume method. Two types of TWVG are used, namely flat trapezoidal winglet (FTW) and curved trapezoidal winglet (CTW), either arranged in common flow up (CFU) or in common flow down (CFD) arrangements. In this study, Reynolds number (Re), angle of attack (β) and aspect ratio (Ʌ) in the range of 500–2500, 10–90° and 2–3 were used respectively. From the experimental study, the results show that the heat transfer can be enhanced by using certain TWVG geometry, arrangement, Ʌ and β to reduce the wake region size at the rear portion of the tubes. Meanwhile, from the numerical simulation, augmentation towards the heat transfer rate is normally accompanied with higher pressure drop penalty. It is inferred that FTW in CFU arrangement at Λ = 3 and β = 10° was found to give the best thermal and hydraulic performance across the FTHE channel when both heat transfer enhancement and pressure drop penalty are considered.

Numerical Evaluation of Thermal Hydraulic Performance in Fin-and-Tube Heat Exchangers With Various Vortex Generator Geometries Arranged in Common-Flow-Down or Common-Flow-Up

Vortex generator as secondary flow enhancement technique has captured the attention of many researchers recently to augment the performance of the fin-and-tube heat exchanger (FTHE). There are various vortex generator parameters that influence the thermal and hydraulic performance in the FTHE such as the geometry and arrangement. In this study, the effect of different vortex generator geometries and arrangements was investigated using numerical simulation method. There are three vortex generator geometries studied including rectangular winglet (RWVG), delta winglet (DWVG), and trapezoidal winglet (TWVG). The vortex generators were placed behind tubes either in common flow down (CFD) or common flow up (CFU) arrangement. The introduction of vortex generators behind tubes resulted in heat transfer augmentation but comes together with higher pressure drop penalty. Further analysis on the thermal performance has found that TWVG in CFU arrangement almost obtained similar thermal performance factor with respect to the baseline case at Reynolds number 500 and 600. However, the thermal performance factor for TWVG in CFU arrangement decreases as the Reynolds number further increased. For other vortex generator cases, lesser thermal performance factor was found as compared to the baseline case.

Comparison and analysis of the arrangement of delta winglet pair vortex generators in a half coiled jacket for heat transfer enhancement

In this paper, multiple delta winglet pairs (DWP) vortex generators were periodically mounted on the heated wall of the half coiled jacket to reinforce heat transfer capability. The jacket is approximated as a helical duct with semicircular cross section. The height of DWP is half the jacket pipe and the circumferential spacing angle between the adjacent DWPs is fixed as θ1 = 90°. Numerical investigations were performed to compare fluid flow and heat transfer performance in jackets (Re = 4000–18,000) under four types of DWP arrangement. Results according to the present study show that the common-flow-up (CFU) configuration of DWP has more advantages in heat transfer enhancement than the common-flow-down (CFD) one. The DWP with CFU-V arrangement provides best overall heat transfer performance when the attack angle β of DWP is between 25° and 30°. This is due to stronger vortices produced by it, slower dissipation of the coupled vortices and subsequently emerged additional vortices. Its comprehensive evaluation factors JF range is from 1.005 to 1.082. The comprehensive heat transfer enhancement effect of CFU-V DWP decreases with the reducing of the jacket curvature ε.

Numerical investigation for the optimal placements of rectangular vortex generators for improved thermal performance of fin-and-tube heat exchangers

In the present work, a numerical investigation has been performed to find out the best emplacement of rectangular winglet pairs (RWPs) for the improvement of the heat transfer and flow characteristics of a fin and tube compact heat exchanger at low Reynolds number ranges from 500 to 900. The RWPs are placed at two different locations i.e., adjacent to the tubes and behind the tubes namely, common-flow-up (CFU) and common-flow-down (CFD) orientations respectively. The effect of attack angle, span angle and location of RWPs on air-side thermal hydraulic performance is investigated numerically. Area goodness factor and heat transfer rate per unit fan power are considered as the performance evaluation criteria. It is found that with the increase in attack angle and span angle heat transfer rate increases causing an increase in pressure drop penalty as well. Vortex generators behind the tube can reduce the pressure drop but with a significant reduction in heat transfer. Furthermore, MOORA (Multi-objective optimization by ratio analysis) method is employed to obtain the most expedient position and orientation of RWPs.

THE EFFECT OF VORTEX GENERATOR BASE LENGTH ON THERMAL HYDRAULIC PERFORMANCE ACROSS FIN-AND-TUBE HEAT EXCHANGER

Heat transfer enhancement is believed can be achieved by using vortex generator. In the past decades, many researches have been performed to investigate the effect of various vortex generator geometry and parameters including vortex generator angle of attack and height. However, less study has been conducted to investigate the influence of vortex generator length at different arrangement towards the heat transfer performance across the fin-and-tube heat exchanger (FTHE). Therefore, the effects of different strategy on the rectangular winglet vortex generator (RWVG) base length towards the thermal hydraulic performance across the FTHE were numerically investigated in this study. Two types of RWVG arrangement known as common flow down (CFD) or common flow up (CFU) arrangement were used and placed behind four rows of tube in inline arrangement. Total of 7 cases were investigated including the default RWVG, extended front and extended back for both RWVG in CFD and CFU arrangement together with FTHE without vortex generator which was set as the baseline case. The Reynolds number ranged from 500 to 900. It was found that the size of the wake region behind the RWVG contributed to the additional pressure drop penalty across the FTHE. Meanwhile, different thermal characteristics were found for different base length strategy in CFD and CFU arrangement. For RWVG arranged in CFD and CFU arrangement, the extended back case shows the highest heat transfer enhancement with 5 – 25 % and 5 – 15 % increment compared to the baseline case respectively. Based on JF factor evaluation, default RWVG in CFU arrangement provide better heat transfer enhancement than the pressure drop penalty compared to other RWVG cases with average JF factor value is 0.8. Nonetheless, none of the tested cases shows higher JF factor value than the baseline case.

Effect of Rectangular Winglet Pair in Common Flow Down Configuration on Heat Transfer from an Isothermally Heated Plate

ABSTRACTPresent three-dimensional numerical study aims to investigate the effect of mounting rectangular winglet pair (RWP) on heat transfer enhancement in flow over a flat plate. Computations for incompressible flow of air have been carried out using commercial software ANSYS Fluent. Flow of air has been considered over the surface of an isothermally heated horizontal plate in presence of RWP in the range of Reynolds number from 400 to 2000. Common flow down configuration of RWP has been considered to study the effect of various geometric parameters, such as length of RWP, spacing between leading edges of the winglets and angle of attack of RWP, on flow characteristics and enhancement in heat transfer. Flow and temperature field characteristics have been presented using streamlines and temperature contours near the plate surface and streamlines in cross-stream planes. Enhancement in heat transfer in presence of RWP has been quantified using cross-stream variation of local Nusselt number, streamwise variation of span-averaged Nusselt number and surface-averaged overall Nusselt number.

Flow Visualization of Flat and Curved Trapezoidal Winglet Vortex Generator in Fin-and-Tube Channel in Inline Arrangement

In this study, a flow visualization experiment using the dye injection technique was conducted. Visual observation of the flow characteristics across the scaled up fin-and-tube heat exchanger (FTHE) channel model with and without trapezoidal winglet vortex generator (TWVG) were presented. Four cases of FTHE channel in inline tube arrangement were examined with TWVG at different geometries and arrangements, as well as a case without the vortex generator. The two TWVG geometries used in this study were a flat trapezoidal winglet (FTW) and a curved trapezoidal winglet (CTW) either arranged in common flow up (CFU) or common flow down (CFD) compositions. The Reynolds number (Re) used ranged from 500 to 2500. It was found that with the introduction of TWVG in the FTHE channel, the wake region size behind tubes reduced compared to the baseline case. However, the formation of an additional wake region behind the TWVG was also observed.

A Comprehensive Numerical Study on Thermohydraulic Performance of Fluid Flow in Triangular Ducts with Delta-Winglet Vortex Generators

ABSTRACTTriangular ducts fitted with various kinds of delta-winglet type vortex generators (VGs) are commonly used to achieve compactness and heat transfer enhancement in many industries. Successive locations of VGs on the inner surfaces of the ducts can be arranged in Common Flow Up (CFU) and Common Flow Down (CFD) orientations. In the present numerical study simultaneous effects of orientation and streamwise distance between VGs on triangular fin performance is carried out considering both global and local flow and heat transfer fields. With the configurations considered in this study, a CFD–CFU orientation and a nondimensional streamwise distance of 0.5 is determined as the best configuration. “RNG k-ϵ” turbulence model with “Enhanced wall treatment” option is determined as the best turbulence model to predict the flow fields inside the triangular duct with built-in VGs, for Reynolds number of 5000.

Investigations on the Influence of Flow Migration on Flow and Heat Transfer in Oblique Fin Microchannel Array

In order to scrutinize the coolant mass distribution and its effect to the heat transfer in oblique fin microchannel array, extensive numerical studies are performed on planar oblique fin configuration. Full-domain simulations using common-flow down (CFD) approach are employed to provide better insights into the flow distribution, flow stability, and heat transfer performance at a global level. The flow field and temperature profile analysis shows that nonuniform coolant distribution and coolant migration occur in the oblique fin microchannel, and the heat transfer performance for both edges of the heat sink is affected due to changing secondary flow rate. However, the flow migration does not affect the local coolant velocity and temperature profiles significantly in the middle region (0.2 < Z′ < 0.8). Meanwhile, it is also found that Reynolds number affects the coolant migration, the stability of the fluid flow, and heat transfer performance significantly. Higher Reynolds number increases the percentage of secondary flow rate and, hence, enhances the heat transfer for fin surfaces in secondary channels.