Simulation of Droplet Impingement on Solid Surface by the Level Set Method and Phase Field Method

The simulation of multi-phase flow with moving interfaces is important in a wide range of applications, such as ink-jet printing, metal depositions, spray cooling, and biomedical engineering applications. Level Set and Phase Field methods are two well-known techniques for tracking the moving interfaces. Each model has its own strength and weakness. This paper compares the two surface tracking models in the simulation of droplet impingement process. The simulations are carried out by employing the Level Set and Phase Field models in COMSOL. The dynamic impingement processes is presented for a glycerin droplet impacting a non-wetting wax surface. The simulated spreading factor and apex height are compared with experimental results for the two surface tracking models

Analysis of A Counter Flow Parallel-Plate Heat Exchanger

Heat exchangers are used widely in many industries for heat recovery or cooling purposes. This paper developed a numerical model to simulate a counter flow parallel heat exchanger. A representative repeating unit cell of the multi-channeled heat exchanger was taken as the computational domain, which includes a cold channel and a hot channel separated by plates. The model was simulated in COMSOL for an oil to water heat exchanger. Higher temperature oil and relatively lower temperature water entered two separate parallel channels in opposite directions. The detailed distributions of temperature, velocity, and pressure were used to analyze the performance of the heat exchanger. It was found the model can be used to provide guidance for designing an optimal heat exchanger

Shape optimization design and material selection for a fitness equipment

Recently, engineers still pay attention to the design of bar structure. For their simple shape and simple manufacture process, a lighter and cheaper bar structure was demanded. As the bar structure is used widely in people’s daily life, there is a fairly useful example for bar structure design. In this project, the Finite Element Method (FEM) was applied to design the bar structures of the fitness equipment. The principle stress and deformation of the equipment by a load that simulate the body weight was predicted by the FEM software (ANSYS). According to the result, the requirement of the material properties was found. The Yield Stress must be lower than the maximum stress, which means this equipment will not be broken at the load. The thickness of the bar and the maximum principle stress was set for a parametric study. For this step, the minimum volume was found. There are many different ways to select an appropriate material. In this project, the CES Edupack was used to select the material

Numerical Simulation of the Dynamics of Water Droplet Impingement on a Wax Surface

The impact of droplets on solid surfaces is important for a wide range of engineering applications, such as ink-jet printing, spray cooling of hot surfaces, spray coating and painting, solder-drop deposition, blood spattering for criminal forensics and disease detection, etc. This paper simulated the dynamic process of a water droplet impinging onto a wax substrate in COMSOL, using the Phase Field method for tracking the free surface. The predicted spreading factor and apex height were validated against experimental results, showing good agreement during the dynamic impingement process. The effect of contact angles on the impingement process was also studied. The initial inertia driven spreading process is not affected by the contact angle, but the later spreading process and recoil process are significantly affected by the contact angle. The simulation results can provide a good understanding of the dynamic impingement process and provide insights on how surface wettability can affect the droplet spreading and rebounding process