Analytical Investigation of Gaussian Roughness Effects on the Thermal Performance of Conical Microfins

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
A. Ayoobi ◽  
M. Ramezanizadeh
Keyword(s):  
Surface Roughness ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Adomian Decomposition Method ◽  
Analytical Investigation ◽  
Roughness Effects ◽  
Nusselt Numbers ◽  
Adomian Decomposition ◽  
Present Solution ◽  
Transfer 21

Effects of Gaussian surface roughness on different aspects of thermal performance of conical microfins are investigated. A new analytical model is developed, applying the Adomian decomposition method. Convergence of the Adomian solution to the exact solution is shown, by increasing the number of computed decomposition terms. In addition, to verify the present solution, the obtained results are compared with the analytical results of Bahrami et al. (2007, “Role of Random Roughness on Thermal Performance of Microfins,” J. Thermophys. Heat Transfer, 21(1), pp. 153–157) for the uniform cross-section microfin. Surface roughness effects on temperature distribution, base heat flux at different Nusselt numbers, and thermal resistance of the microfin are investigated. It is observed that the thermal resistance of the smooth microfin is higher than the rough one and by increasing the roughness, the thermal resistance experiences further reduction.

CFD Modelling Strategies for the Simulation of Roughness Effects on Friction and Heat Transfer in Additive Manufactured Components

2020 ◽  
Author(s):  
Lorenzo Mazzei ◽  
Riccardo Da Soghe ◽  
Cosimo Bianchini
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Thermal Performance ◽  
Accurate Estimation ◽  
Real Surface ◽  
Cfd Modelling ◽  
Roughness Effects ◽  
Modelling Strategies ◽  
The Impact ◽  
Grain Roughness

Abstract It is well-known from the literature that surface roughness affects significantly friction and heat transfer. This is even more evident for additive manufactured (AM) components, which are taking an increasingly important role in the gas turbine field. However, the exploitation of numerical approaches to improve their design is hindered by the lack of dedicated correlations and CFD model developed for such high roughness conditions. Usually the additive manufactured components are simulated considering the surfaces as smooth or applying an equivalent sand-grain roughness (ks) that results in a velocity shift in the boundary layer. However, determining a priori the most appropriate value of ks is challenging, as dozens of correlations are available, returning scattered and uncertain results. The aim of this work is to benchmark some existing modelling strategies (among which the equivalent sand grain roughness) and test a numerical approach capable of narrowing the existing gap between simulated and tested thermal performance of additive manufactured devices. The technology enabler is represented by higher-fidelity CFD simulations accounting for the impact of real surface roughness on pressure drop and heat transfer. At this purpose, an existing literature model for rough walls has been implemented in ANSYS Fluent and tested on a variety of AM mini-channels so as to determine the best-fitting values of ks and corrected wetted surface ratio Scorr that match the experimental data in terms of friction factor and Nusselt number. Knowing also the measured roughness descriptors of each component, it has been possible to derive valuable guidelines for an effective exploitation of CFD on additive manufactured components, thus allowing a more accurate estimation of the thermal performance in additive manufactured components.

scholarly journals Analytical Investigation of Noyes–Field Model for Time-Fractional Belousov–Zhabotinsky Reaction

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Mohammed Kbiri Alaoui ◽  
Rabia Fayyaz ◽  
Adnan Khan ◽  
Rasool Shah ◽  
Mohammed S. Abdo
Keyword(s):  
Fractional Order ◽  
Homotopy Perturbation Method ◽  
Adomian Decomposition Method ◽  
Analytical Techniques ◽  
Analytical Investigation ◽  
Physical Problems ◽  
Adomian Decomposition ◽  
The Given ◽  
Belousov Zhabotinsky Reaction ◽  
Belousov Zhabotinskii Reaction

In this article, we find the solution of time-fractional Belousov–Zhabotinskii reaction by implementing two well-known analytical techniques. The proposed methods are the modified form of the Adomian decomposition method and homotopy perturbation method with Yang transform. In Caputo manner, the fractional derivative is used. The solution we obtained is in the form of series which helps in investigating the analytical solution of the time-fractional Belousov–Zhabotinskii (B-Z) system. To verify the accuracy of the proposed methods, an illustrative example is taken, and through graphs, the solution is shown. Also, the fractional-order and integer-order solutions are compared with the help of graphs which are easy to understand. It has been verified that the solution obtained by using the given approaches has the desired rate of convergence to the exact solution. The proposed technique’s principal benefit is the low amount of calculations required. It can also be used to solve fractional-order physical problems in a variety of domains.

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