layer problem
Recently Published Documents


TOTAL DOCUMENTS

210
(FIVE YEARS 20)

H-INDEX

20
(FIVE YEARS 1)

2022 ◽  
Author(s):  
Yair Zarmi

Abstract In view of interest in relativistic harmonic oscillations in media, through which the speed of light is orders of magnitude smaller than in vacuum, the solution of the equation of motion is analyzed in the extreme- and weak-relativistic limits. Using scaled variables, it is shown rigorously how the equation of motion exhibits the characteristics of a boundary-layer problem in the extreme-relativistic limit: The solution differs from a sharp asymptotic pattern only around the turning points of oscillations over a vanishingly small fraction of the period. The sharp asymptotic pattern of the solution is a saw-tooth composed of linear segments. The velocity profile tends to a periodic step function and the phase-space plot tends to a rectangle. An expansion of the solution in terms of a small parameter that measures the proximity to the limit (v/c) → 1 yields an excellent approximation for the solution throughout the whole period of oscillations. In the weak-relativistic limit the same approach yields an approximation to the solution that is significantly better than in traditional asymptotic expansion procedures.


Author(s):  
N.V. Sandalyuk ◽  
◽  
V.G. Gnevyshev ◽  
T.V. Belonenko ◽  
Vladimirovich Kochnev ◽  
...  

2020 ◽  
Vol 14 (3) ◽  
pp. 7296-7308
Author(s):  
Siti Nur Humaira Mazlan ◽  
Aini Zuhra Abdul Kadir ◽  
N. H. A. Ngadiman ◽  
M.R. Alkahari

Fused deposition modelling (FDM) is a process of joining materials based on material entrusion technique to produce objects from 3D model using layer-by-layer technique as opposed to subtractive manufacturing. However, many challenges arise in the FDM-printed part such as warping, first layer problem and elephant food that was led to an error in dimensional accuracy of the printed parts especially for the overhanging parts. Hence, in order to investigate the manufacturability of the FDM printed part, various geometrical and manufacturing features were developed using the benchmarking artifacts. Therefore, in this study, new benchmarking artifacts containing multiple overhang lengths were proposed. After the benchmarking artifacts were developed, each of the features were inspected using 3D laser scanner to measure the dimensional accuracy and tolerances. Based on 3D scanned parts, 80% of the fabricated parts were fabricated within ±0.5 mm of dimensional accuracy as compared with the CAD data. In addition, the multiple overhang lengths were also successfully fabricated with a very significant of filament sagging observed.


2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Emad H. Aly ◽  
Abdelhalim Ebaid

Purpose The purpose of this paper is to study flow of the Marangoni boundary layer pasta surface embedded in a porous medium saturated by a hybrid nanofluid in the presence of a magnetic field and thermal radiation. Design/methodology/approach The governing model was converted into ordinary differential equations applying proper similarity transformations. Therefore, Laplace transform was used to exactly solve the resulted equations. Hence, the influence of the velocity profile and temperature distribution was investigated under impacts of the involved parameters. Findings In the case of regular fluid, i.e. the solid volume fractions are zeros, the current results are in a very good agreement with those in the literature. It was found that the velocity decreases (increases) on increasing the parameters of copper-nanoparticles volume fraction, magnetic field and suction (permeability and injection). Further, the temperature increases (decreases) with an increase of the copper-nanoparticles volume fraction, magnetic field, injection and radiation (permeability and suction). Originality/value The current results of the Marangoni boundary layer problem for hybrid nanofluids are new, original and extend the previous problems investigated by many authors for the case of regular/nano fluids.


Sign in / Sign up

Export Citation Format

Share Document