Numerical Study on Substrate Remelting, Flow, and Resolidification in Microcasting

Volume 3 ◽  
2004 ◽  
Author(s):  
F. J. Hong ◽  
H.-H. Qiu
Keyword(s):  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Numerical Study ◽  
Thermal Contact ◽  
Spreading Factor ◽  
Droplet Spreading ◽  
Molten Droplet ◽  
Front Shape ◽  
Complex Fluid

A large and highly superheated molten droplet impacting onto the substrate during the microcasting was studied numerically. In this study, same material for both the droplet and the substrate was considered. Numerical model including the complex fluid dynamics of droplet, interfacial thermal contact resistance, and substrate remelting, as well as the flow in the substrate has been developed. Numerical simulations of a microcasting experiment were conducted with the different thermal contact resistances. The results of simulations show that the spreading factor and substrate remelting agreed well with the experimental data under the assumption of an appropriate thermal contact resistance. It is also found that the thermal contact resistance plays an important role not only in droplet spreading arrest but also in the determination of substrate remelting volume and remelting front shape. The effects of droplet impacting velocity, superheat and substrate temperature were also investigated.

Effect of Thermal Contact Resistance on Alumina Molten Particle Impacting onto a Metal Substrate

2012 ◽  
Vol 326-328 ◽  
pp. 482-487 ◽  
Author(s):  
S. Oukach ◽  
Bernard Pateyron ◽  
H. Hamdi ◽  
M. El Ganaoui
Keyword(s):  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Droplet Diameter ◽  
Thermal Contact ◽  
Thermal Spraying ◽  
Droplet Spreading ◽  
Element Analysis ◽  
Molten Droplet ◽  
Molten Droplets ◽  
Droplet Sizes

In this paper, a Finite Element Analysis is carried out in order to simulate the process of spreading and solidification of a micrometric molten droplet impinging onto a cold substrate. This process is a crucial key to have a good understanding of coatings obtained by means of thermal spraying. The effect of thermal contact resistance (TCR) on the droplet spreading and solidification was investigated using different values of TCR and different droplet sizes. The solidification time was found to be a linear function of the droplet diameter square. Viscous dissipation, wettability and surface tension effects are taken into account. The Level Set method was employed to explicitly track the free surface of molten droplets.

Numerical Determination of Thermal Contact Resistance for Nonisothermal Forging Processes

2000 ◽  
Vol 122 (4) ◽  
pp. 776-784 ◽  
Author(s):  
A.-S. Marchand ◽  
M. Raynaud
Keyword(s):  
Thermal Properties ◽  
Finite Difference Method ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Numerical Study ◽  
Thermal Contact ◽  
Numerical Determination ◽  
Predictive Capability ◽  
Interface Geometry

A numerical study is conducted to estimate the thermal contact resistance (TCR) between the tool and the workpiece during slow nonisothermal forging processes. A finite difference method is used to determine the TCR from a thermomechanical microscopic model. Correlations of the numerical results are developed for the TCR as a function of the interface geometry and the thermal properties. The method used to introduce these correlations in forging softwares, to account for a time and space-dependent TCR instead of a constant arbitrary value, is given. The predictive capability of the correlations is partially validated by comparing their outputs with TCR results from the literature. [S0022-1481(00)00903-8]

Deformation and Solidification of Droplet Impact With Variable Thermal Contact Resistance

2003 ◽  
Author(s):  
W. Wang ◽  
H.-H. Qiu ◽  
P. Cheng
Keyword(s):  
Numerical Simulation ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Solidification Process ◽  
Numerical Results ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Molten Droplet ◽  
Comparison Results

Interfacial thermal contact resistance between the impinging flow of a molten droplet and a substrate, which is qualified by thermal contact conductance, plays an important role in the spreading and solidification of a droplet. In the present study, a simple correlation for the thermal contact conductance in the rapid contact solidification process was developed. With this correlation being directly used in numerical simulation, for the first time, a variable thermal contact resistance was taken into consideration to simulate both the dynamics and phase change responses during a molten droplet impingement. Numerical results were compared with that of the cases when thermal contact resistance was zero or a constant. The changes in spread factor with time and thermal contact conductance indicated that predictions from the computer simulation were sensitive to the values of thermal contact resistance. Experiment was conducted to demonstrate the validity of the present study. Comparison results showed that rather than using a constant average value, better agreement between the experimental and numerical results would be obtained if a variable thermal contact resistance were used in the numerical simulation.

Application of Thermal Contact Resistance in Simulation of Heat Dissipation by CPU Heat Sinks Based on ANSYS

2014 ◽  
Vol 941-944 ◽  
pp. 2465-2468 ◽  
Author(s):  
Yong Zhen Liu ◽  
Zhi Shi Huang ◽  
Bin Feng ◽  
Jin He Wei ◽  
Jian Min Zeng
Keyword(s):  
Contact Resistance ◽  
Heat Dissipation ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Heat Sinks ◽  
Ansys Software ◽  
Electronic Elements ◽  
Good Heat ◽  
Main Factor

With development in electronic technology, more and more electronic elements have been integrated into one chip, which has resulted in the cooling problem of the chips. In this case, heat dissipation has become the main factor that affecting the design reliability and package cost. Therefore, good heat dissipation designs are urgently need to solve the problem. An important issue resulted from simulation of heat dissipation is the determination of boundary condition between the heat sink and the CPU. The concept of thermal contact resistance was introduced to simulation of heat dissipation of CPU heat sinks in this paper. The temperature distribution of CPU heat sinks was calculated Based on ANSYS software. The result of calculation can help to understand the heat transfer characteristics of CPU heat sinks, and also offer a reference for the design and improvement of the electronic equipment.

Extrapolation Errors in Thermal Contact Resistance Measurements

1975 ◽  
Vol 97 (2) ◽  
pp. 305-307 ◽  
Author(s):  
T. R. Thomas
Keyword(s):  
Temperature Gradient ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Temperature Drop ◽  
Interface Temperature ◽  
Better Than

In the classic split-bar determination of thermal contact resistance the temperature drop across the interface is estimated by extrapolating a temperature gradient measured remotely. It is shown that this can give rise to substantial errors which cannot greatly be reduced by increasing the number of measurements. It is suggested that due to extrapolation errors few interface temperature drops have ever been determined to better than 1/2 °K, and that this may account for some of the discrepancies between published contact resistances, particularly those measured at high loads.

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