Numerical Solution for a Transient Temperature Distribution on a Finite Domain Due to a Dithering or Rotating Laser Beam

2013 ◽  
Vol 4 (4) ◽  
pp. 22-38
Author(s):  
Tsuwei Tan ◽  
Hong Zhou
Keyword(s):  
Temperature Distribution ◽  
Laser Beam ◽  
Temperature Rise ◽  
Maximum Temperature ◽  
Finite Domain ◽  
Transient Temperature ◽  
Gaussian Laser Beam ◽  
Maximum Temperature Rise ◽  
Transient Temperature Distribution ◽  
Spatial Dimensions

The temperature distribution due to a rotating or dithering Gaussian laser beam on a finite body is obtained numerically. The authors apply various techniques to solve the nonhomogeneous heat equation in different spatial dimensions. The authors’ approach includes the Crank-Nicolson method, the Fast Fourier Transform (FFT) method and the commercial software COMSOL. It is found that the maximum temperature rise decreases as the frequency of the rotating or dithering laser beam increases and the temperature rise induced by a rotating beam is smaller than the one induced by a dithering beam. The authors’ numerical results also provide the asymptotic behavior of the maximum temperature rise as a function of the frequency of a rotating or dithering laser beam.

Heat Partition and Transient Temperature Distribution in Layered Concentrated Contacts. Part II—Dimensionless Relationships and Numerical Results

1987 ◽  
Vol 109 (3) ◽  
pp. 496-501 ◽  
Author(s):  
M. Rashid ◽  
A. Seireg
Keyword(s):  
Temperature Distribution ◽  
Temperature Rise ◽  
Surface Coating ◽  
Numerical Results ◽  
Operating Conditions ◽  
Transient Temperature ◽  
Transient Temperature Distribution ◽  
Heat Partition ◽  
Recent Interest ◽  
Computer Based

The computer-based model described in Part I is utilized in this paper to develop dimensionless relationships for lubricated unlayered contacts and dry layered contacts. Because of the recent interest in tribological surface coating these relationships can be used to provide parametric evaluations of heat partition and temperature rise in the contacts under different coating parameters and operating conditions.

A Fractal Theory of the Temperature Distribution at Elastic Contacts of Fast Sliding Surfaces

1995 ◽  
Vol 117 (2) ◽  
pp. 203-214 ◽  
Author(s):  
S. Wang ◽  
K. Komvopoulos
Keyword(s):  
Fractal Dimension ◽  
Temperature Distribution ◽  
Contact Area ◽  
Temperature Rise ◽  
Maximum Temperature ◽  
Real Contact Area ◽  
The Real ◽  
Sliding Surfaces ◽  
Real Contact ◽  
Maximum Temperature Rise

The statistical temperature distribution at fast sliding interfaces is studied by characterizing the surfaces as fractals and considering elastic deformation of the asperities. The fractions of the real contact area in the slow, transitional, and fast sliding regimes are determined based on the microcontact size distribution. For a smooth surface in contact with a rough surface, the temperature rises at the real contact area are determined under the assumption that most of the frictional heat is transferred to one of the surfaces. The interfacial temperature rises are bounded by the maximum temperature rise at the largest microcontact when the fractal dimension is 1.5 or less, and are unbounded when it is greater than 1.5. Higher temperature rises occur at larger microcontacts when the fractal dimension is less than 1.5, and at smaller microcontacts when it is greater than 1.5. For a fractal dimension of 1.5, the maximum temperature rise at a microcontact is independent of its size. The maximum temperature rise at the largest microcontact is expressed as a function of the friction coefficient, sliding speed, elastic and thermal properties, real and apparent contact areas, and fractal parameters. The closed-form solutions for the distribution density function of the temperature rise can be used to calculate the fraction of the real contact area of fast sliding surfaces subjected to temperature rises in any given range. The present theory is applied to boundary-lubricated and dry sliding contacts to determine the fractions of the real contact area where lubricant degradation and thermal surface failure may occur.

scholarly journals Transient temperature distribution on the corneal endothelium during ophthalmic phacoemulsification: a numerical simulation using the nodeless variable element

2010 ◽  
Vol 4 (6) ◽  
pp. 885-892 ◽  
Author(s):  
Wiroj Limtrakarn ◽  
Somporn Reepolmaha ◽  
Pramote Dechaumphai
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Anterior Chamber ◽  
Heat Generation ◽  
Corneal Endothelium ◽  
Temperature Response ◽  
Maximum Temperature ◽  
Transient Temperature ◽  
Cataract Operation ◽  
Transient Temperature Distribution

Abstract Background: During cataract operation (phacoemulsification), a phaco needle-tip is inserted into the anterior chamber of eye. Then, heat is generated by the oscillation of the phaco needle, which may injury the corneal endothelial cells. There are no data available for temperature responses at the corneal endothelium to heat from the phaco needle during phacoemulsification. Objective: Investigate temperature distribution on the corneal endothelium during ophthalmic phacoemulsification using numerical simulation, and compare the transient temperature response to heat between balanced salt solution (BSS) and ophthalmic viscoelastic device (OVD), Viscoat®. Methods: Heat flux from a phaco needle was measured with thermal properties of BSS and AVS in an experimental setting. Then, nodeless variable finite element method was applied to predict temperature changes in the eye by the phaco needle inserted into the anterior chamber. The transient temperature distribution on the corneal endothelium was calculated at 10, 20, and 30 seconds after heat generation by the needle. Results: The heat generation of phaco needle without sleeve cover was 1.6 kW/m2. The numerical simulation showed that the maximum temperature occurs on the wound location at all times after heat generation by the phaco needle. Especially, at time 30 seconds, it was 49.2 and 41.7°C in BSS and OVD, respectively. The temperature elevation by the phaco needle was lower in OVD than BSS. Conclusion: Phacoemulsification is a heat-generating procedure performed between the anterior chamber structures of eye. During this procedure, OVD may protect the corneal endothelium against heat better than BSS.

Modeling temperature rise in multi-track reciprocating frictional sliding

2021 ◽  
pp. 135065012098823
Author(s):  
Thierry A Blanchet
Keyword(s):  
Temperature Rise ◽  
Peclet Number ◽  
Maximum Temperature ◽  
Uniform Heat Flux ◽  
Heat Accumulation ◽  
Stroke Length ◽  
Péclet Number ◽  
Maximum Temperature Rise ◽  
Rectangular Patch ◽  
Accumulation Effect

As in various manufacturing processes, in sliding tests with scanning motions to extend the sliding distance over fresh countersurface, temperature rise during any pass is bolstered by heating during prior passes over neighboring tracks, providing a “heat accumulation effect” with persisting temperature rises contributing to an overall temperature rise of the current pass. Conduction modeling is developed for surface temperature rise as a function of numerous inputs: power and size of heat source; speed and stroke length, and track increment of scanning motion; and countersurface thermal properties. Analysis focused on mid-stroke location for passes of a square uniform heat flux sufficiently far into the rectangular patch being scanned from the first pass at its edge that steady heat accumulation effect response is adopted, focusing on maximum temperature rise experienced across the pass' track. The model is non-dimensionalized to broaden the applicability of the output of its runs. Focusing on practical “high” scanning speeds, represented non-dimensionally by Peclet number (in excess of 40), applicability is further broadened by multiplying non-dimensional maximum temperature rise by the square root of Peclet number as model output. Additionally, investigating model runs at various non-dimensional speed (Peclet number) and reciprocation period values, it appears these do not act as independent inputs, but instead with their product (non-dimensional stroke length) as a single independent input. Modified maximum temperature rise output appears to be a function of only two inputs, increasing with decreasing non-dimensional values of stroke length and scanning increment, with outputs of models runs summarized compactly in a simple chart.

Direct observation of three-dimensional transient temperature distribution in SiC Schottky barrier diode under operation by optical-interference contactless thermometry (OICT) imaging

2022 ◽  
Author(s):  
Keiya Fujimoto ◽  
Hiroaki Hanafusa ◽  
Takuma Sato ◽  
Seiichiro HIGASHI
Keyword(s):  
Temperature Distribution ◽  
Schottky Barrier ◽  
Hot Spot ◽  
Local Heating ◽  
Three Dimensional ◽  
Schottky Barrier Diode ◽  
Transient Temperature ◽  
Optical Interference ◽  
Transient Temperature Distribution ◽  
Heating And Cooling

Abstract We have developed optical-interference contactless thermometry (OICT) imaging technique to visualize three-dimensional transient temperature distribution in 4H-SiC Schottky barrier diode (SBD) under operation. When a 1 ms forward pulse bias was applied, clear variation of optical interference fringes induced by self-heating and cooling were observed. Thermal diffusion and optical analysis revealed three-dimensional temperature distribution with high spatial (≤ 10 μm) and temporal (≤ 100 μs) resolutions. A hot spot that signals breakdown of the SBD was successfully captured as an anormal interference, which indicated a local heating to a temperature as high as 805 K at the time of failure.

Measurement of Transient Temperature Distribution at Anode Surface After Current Zero in Vacuum Interrupter

2021 ◽  
Vol 141 (11) ◽  
pp. 712-717
Author(s):  
Akira Daibo ◽  
Yoshimitsu Niwa ◽  
Naoki Asari ◽  
Wataru Sakaguchi ◽  
Yo Sasaki ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Anode Surface ◽  
Transient Temperature ◽  
Vacuum Interrupter ◽  
Transient Temperature Distribution ◽  
Current Zero

Braking performance of a novel frictional-magnetic compound disc brake for automobiles

2018 ◽  
Vol 233 (10) ◽  
pp. 2443-2454 ◽  
Author(s):  
Yan Yin ◽  
Jiusheng Bao ◽  
Jinge Liu ◽  
Chaoxun Guo ◽  
Tonggang Liu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Temperature Rise ◽  
Friction Material ◽  
Maximum Temperature ◽  
Interface Temperature ◽  
Disc Brake ◽  
Braking Performance ◽  
Maximum Temperature Rise ◽  
Disc Brakes ◽  
Braking Torque

Disc brakes have been applied in various automobiles widely and their braking performance has vitally important effects on the safe operation of automobiles. Although numerous researches have been conducted to find out the influential law and mechanism of working condition parameters like braking pressure, initial braking speed, and interface temperature on braking performance of disc brakes, the influence of magnetic field is seldom taken into consideration. In this paper, based on the novel automotive frictional-magnetic compound disc brake, the influential law of magnetic field on braking performance was investigated deeply. First, braking simulation tests of disc brakes were carried out, and then dynamic variation laws and mechanisms of braking torque and interface temperature were discussed. Furthermore, some parameters including average braking torque, trend coefficient and fluctuation coefficient of braking torque, average temperature, maximum temperature rise, and the time corresponding to the maximum temperature rise were extracted to characterize the braking performance of disc brakes. Finally, the influential law and mechanism of excitation voltage on braking performance were analyzed through braking simulation tests and surface topography analysis of friction material. It is concluded that the performance of frictional-magnetic compound disc brake is prior to common brake. Magnetic field is greatly beneficial for improving the braking performance of frictional-magnetic compound disc brake.

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