Abstract
As is well known, micro/nanoscale fluid flow and heat transfer have become one of the hottest research topics in mechanical engineering, chemical engineering, electronic engineering, energy engineering, biomedical engineering, and so on. Inspired by the latest advances in micro/nanoscale fluid flow and heat transfer, this special theme issue is devoted to collecting innovative and high-quality research contributions regarding the recent advances in micro/nanoscale fluid flow and heat transfer. A total of 12 submissions were selected for publication after two rounds of peer-reviews. In the following, we briefly discuss each accepted paper to provide an overview of this special theme issue:
The paper titled “CFD simulation of sub cooled flow boiling in vertical rectangular 2 mm narrow channel” developed a new wall boiling model which provides better predictions of the distribution of wall temperature in a 2-mm narrow channel as compared with the default model already developed in the CFX Software Code.
In the contribution titled “Dynamics of ferromagnetic nanowires in a rotating magnetic field,” an analytical model was developed to investigate the motion of ferromagnetic nickel nanowires under a rotating magnetic field. The theoretical prediction showed very good agreement with the experimental data, which demonstrated that the model can be applied to future exploration of magnetic manipulation of nanowires.
The study titled “Effects of liquid morphology and distribution on the apparent properties of porous media made of stacked particles” focused on the effect of the liquid morphology on the apparent transfer properties of porous media formed by stacked particles. A model was developed for predicting the critical liquid content at which the liquid morphology shifts from the state of liquid bridges into the state of interconnectedness. The prediction from the model was in good agreement with the experiment.
In the work titled “Analysis of flow boiling heat transfer in narrow annular gaps applying the design of experiments—method,” the axial heat transfer coefficient during flow boiling of n-hexane was measured using infrared thermography. The authors presented two correlations between the heat transfer coefficient and the operating parameters.
The paper titled “Numerical analysis and parametric study of multi-layered microchannel heat sinks” investigated and optimized the performances of two-, three-, and four-layered microchannel heat sinks based on a three-dimensional solid–fluid conjugate model. More uniform temperature distribution and lower thermal resistance for the microchannel heat sinks were achieved after optimization. In addition, useful results such as “the multi-layered heat sink with more layer number can achieve a more uniform bottom wall temperature” were also presented.
In the contribution titled “A model for analyzing temperature profiles in pipe walls and fluids using mathematical experimentation,” by remodeling Poiseuille’s equation, temperature profiles among pipe wall, fluid flow, and surrounding air were investigated, and a new dimensionless parameter (unified number) was also introduced.
The theoretical work titled “An analytical model of thermal conductivity for carbon/carbon composites with pitch-based matrix” proposed a nanoscale sub-model to describe the thermal conductivity of the matrix based on its micro-structure. Then, the sub-model is incorporated into a micro-scale model to analytically predict the equivalent thermal conductivities of the composites. The result predicted by the model agrees well with the experimental measurements. Many interesting results were achieved.
The paper titled “A theoretical comparative study on nano-refrigerant performance in a single-stage vapor compression refrigeration cycle” developed a method to estimate the performance characteristics of nano-refrigerants in the refrigerant cycles. The results indicated that the coefficient of performance for various evaporation and condensation temperatures was enhanced by adding nanoparticles to the pure refrigerant and maximum values obtained using the R600a/Al2O3 mixture.
In the experimental contribution “Preparation and characterization of silver liquid thin films for magnetic fluid deformable mirror,” characterization of silver nanoparticles was studied using X-ray diffractometer, UV-vis spectrophotometer, and transmission electron microscope (TEM). Many useful experimental data were provided in the paper.
In the paper titled “Thermal conductivity prediction of closed-cell aluminum alloy considering micro-pore effect,” a new kind of dual-scale method was proposed to estimate the effective thermal conductivity of closed-cell aluminum alloy. Verified by the experimental results, the prediction accuracy can be improved greatly by the dual-scale method.
The work “Understanding of the interaction between clearance leakage flow and main passage flow in a variable geometry turbine turbine” numerically investigated the clearance flow between the nozzle and end wall in a variable geometry turbine to understand mechanism of the clearance effect on the turbine performance, and two main mechanisms were proposed in the paper.
In the last paper titled “Numerical simulation of a backward-facing step flow in a microchannel with external electric field,” a high-order accuracy upwind compact difference scheme was proposed to solve the Poisson–Boltzmann and Navier–Stokes equations for the investigation of a backward-facing step flow in the microchannel with external electric field, and the results confirmed the ability of the new solver in the simulation of micro-scale electric double layer effects.
Based on the above, each accepted paper is expected to serve as a representative achievement for a specific topic under the theme of this special theme issue. This special theme issue brings a rich blend of theoretical, modeling, and experimental works. The guest editors sincerely appreciate the peer-reviewers who meticulously reviewed each submission. The authors’ cooperation and their important research results are also greatly appreciated. We sincerely hope that all the papers included are attractive to the wider research communities and could provide valuable information to scientists, engineers, and researchers. We also would like to thank the publication office of the journal Advances in Mechanical Engineering for their warm help during the entire process of preparing this special theme issue. Finally, we would like to express that we have greatly enjoyed handling this special theme issue, and we hope that the readers will enjoy it as well.