# Latest Progress and Applications of Multiphase Flow and Heat Transfer
###### Abstract
They conduct Hele-Shaw cell displacement experiments for a miscible fluid system by using skim milk and an aqueous citric acid solution. The effects of gel film formation on fingering instability are discussed and investigated, and a mathematical model is developed for the sequential growth of gel film formation at the fingertip. The results show that mixing skim milk with the aqueous citric acid solution causes the formation of gel film, which leads to interface instability. The diffusion of citric acid causes the formation of gel film to thicken over time. As the flow increases, the width of the fingers remains constant while the finger number increases linearly before the fingers merge. Based on the interaction between the diffusion of citric acid and the elongation of the fingertip, a mathematical model of sequential film thickness growth is developed for a bubble-like fingertip structure. The model is helpful for providing us with a better understanding of the fundamental growth mechanism of the bubble-like fingertip. The fourth article written by scholars from academia (Louisiana State University and University of Texas at Austin) and industry (KBR) in the USA focuses on the influence of porous media on the interaction between wave-induced sloshing and the dynamics of the floating body, which is very important to the structural vibration control in civil and ocean engineering. A numerical algorithm that couples fluid computation (for sloshing fluid and ambient waves) and rigid-body dynamics (for the floating platform) is proposed. The Eulerian-Lagrangian method is employed to calculate the hydrodynamic in both the pore-flow domain and the pure-water domain. The Newmark time integration method is adopted for the rigid body dynamics to ensure numerical stability. The modeling freedom of the sloshing fluid is reduced, and the numerical process is fast and inexpensive. According to the frequency response analysis, the effectiveness of the porous media is verified for reducing the vibration and mitigating the sloshing response. It is believed that the porous media will reduce the hydrodynamic pressure and improve the integrity of the liquid container. In the fifth article, [PERSON] et al. from the Xi'an Jiaotong University of China develop a high-accuracy flow pattern identification method for air-water two-phase flow in the porous media by combining signal feature extraction technologies and machine learning technologies. According to the differential pressure signals of two-phase flow in porous beds, three parameters related to time domain characteristics, including the mean, standard deviation, and range of the signals, are analyzed and extracted using a statistical method. In addition, the time-frequency domain features of the signals are also extracted with the empirical mode decomposition (EMD) method. Then, machine learning technologies, such as the support vector machine (SVM) and BP neural network, are adopted to train and construct different flow pattern identification models based on extracted signal feature parameters. In the end, an online and high-accuracy intelligent system is established to identify the flow patterns in porous media. The sixth article focuses on the enhanced heat transfer characteristics of spherical heat storage related to phase change thermal storage technology. Researchers from the Inner Mongolia Agricultural University and Inner Mongolia Agricultural University of China designed and constructed a test system of melting spherical heat storage units to experimentally study the melting characteristics of a CuO-paraffin wax composite in a spherical heat storage unit. The influences of parameters, including the pin fin numbers, the temperature in the water bath, and the CuO nanoparticles in paraffin, are discussed and analyzed. In addition, a regression model is fitted to investigate the effects of different parameters on the melting time of the phase change material (PCM).