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Today, electronic device cooling is a significant challenge that has been addressed by utilizing heat sinks with various designs. The numerical and experimental investigation of changes in the wavy channel heat sink height is carried out to improve the performance. As a novelty, the heat sink's height remains constant to assess how open space above the channels affects the performance. The work aims to assess the impact of various heat fluxes and flow rates on temperature, Nu number, flow, and velocity; meanwhile conducting a non-dimensional analysis. At the flowrate of 6.94 cm 3 / s , once the channel's height was reduced to 10 mm, the highest temperature decreased by 7.84%, while by the decrement of height to 7 and 4 mm, it witnessed 14.14% and 23.81% rises, respectively. The local Nusselt number for 10 mm height and 19.56 cm 3 / s flow ranges between 127.47 and 106.53 in 5.17 W/cm2 heat flux. The flow with higher dimensionless velocity is dispersed throughout the open area above the heat sink, once the 12.7 mm height is reduced to 10 mm. The performance evaluation criterion of the system is determined by considering the ratio between Nu number and friction factor, which is obtained between 1.08 and 1.22 for 10 mm channel height. Thus, the 10 mm wavy channel height can be suggested for cooling electrical equipment. • Investigating channel height variations in constant-height heat sinks to determine open space impact above the wavy channel. • The wavy channel heat sink with 10 mm height shows higher performance due to flow mixing. • An analysis of velocity and temperature is provided using non-dimensional methods. • The performance evaluation criterion is compared for different channel heights while keeping the heat sink height constant. [ABSTRACT FROM AUTHOR]

• Numerical simulation of steam-liquid two-phase flow in rifled tube with dryout is carried out. • The inhibitory effect of rifled tube on dryout is studied. • Un-uniform of the circumferential wall temperature caused by the distribution of steam and liquid relative content and velocity is studied. • The absolute vorticity flux and secondary flow intensity of rifled tube are quantitatively analyzed. The two-fluid three-flow field mathematical model is used to carry out the numerical simulation of heat transfer characteristics of steam-liquid two-phase flow in dryout and post-dryout region of the rifled tube. The absolute vorticity flux and intensity of the secondary flow are introduced to quantitatively characterize the heat transfer enhancement. The results show that, compared with smooth tube, the rifled tube can greatly reduce the rise of wall temperature and have a significant effect on dryout inhibition. The cross-section wall temperature of rifled tube presents a periodic distribution. The wall temperature at the intersection of the root and rib side is higher due to the fluid retention. After the dryout occurs, the wall temperature is higher than other locations due to the continuous liquid film on the crest being torn. The secondary flow strength and heat transfer enhancement degree of fluid in rifled tube increase with the increase in axial height. The absolute vortex flux, intensity of the secondary flow and absolute value of the vorticity in main flow direction can reflect the degree of fluid disturbance caused by internal thread. [ABSTRACT FROM AUTHOR]