Effects of the viscous dissipation on the Darcy-Brinkman flow: Rigorous derivation of the higher-order asymptotic model

2020 ◽  
Vol 386 ◽  
pp. 125479
Author(s):  
Igor Pažanin ◽  
Marko Radulović
Author(s):  
Григорий Николаевич Белосточный ◽  
Мария Владимировна Вильде ◽  
Мария Юрьевна Сурова

Изучается возможность применения уточненной асимптотической модели планарной краевой волны в задаче о действии нестационарной касательной нагрузки, приложенной на торце. При построении уточненной модели используется асимптотическая двумерная теория растяжения пластин высшего порядка точности. Приводятся результаты сравнения с решением по трехмерной теории упругости для различных законов распределения нагрузки. Показано, что уточненная модель позволяет достаточно точно описать влияние дисперсии краевой волны, не учитываемое в первом приближении. The possibility of application of the refined explicit model for extensional edge wave in the problem of transient waves excitation by an edge tangential load is investigated. The refined model is based on the higher order theory of plate extension. The results of comparison with the 3D solution for various distributions of the load are presented. It is shown that the refined model allows correct describing of dispersion effects which are not taken into account in the leading approximation.


1973 ◽  
Vol 57 (1) ◽  
pp. 1-25 ◽  
Author(s):  
Noor Afzal

A higher order theory for two-dimensional turbulent boundary-layer flow of a compressible fluid past a plane wall is formulated, for moderately large values of the Reynolds number, by the method of matched asymptotic expansions. The parameters (γ − 1) M2∞and the molecular Prandtl number are assumed to be of order unity. The analysis deals with the set of Reynolds equations of mean motion (which are underdetermined without an additional set of closure hypotheses) and assumes that the non-dimensional fluctuations in velocity, temperature and density are of orderU*, (friction velocity divided by free-stream velocity a t some designation point), while fluctuations in pressure are of orderU2*.The first-order results of the present study lead to asymptotic laws for velocity and temperature distributions which correspond to the law of the wall, logarithmic law and defect law, and also to skin friction and heat-transfer laws. It turns out that the first-order defect law depends upon the gradient of entropy and stagnation enthalpy and the law of the wall is independent of viscous dissipation. The second-order terms of the present work (accounting for mean convection due to turbulent mass flux, viscous dissipation in the inner flow and displacement effects in the outer flow) describe the necessary corrections to first-order terms due to low Reynolds number effects. In the overlap region the second-order results, for the law of the wall and the defect law, show bilogarithmic terms along with logarithmic terms.


2021 ◽  
Vol 60 (1) ◽  
pp. 1861-1871
Author(s):  
D. Gopal ◽  
S. Saleem ◽  
S. Jagadha ◽  
Farooq Ahmad ◽  
A. Othman Almatroud ◽  
...  

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.


Author(s):  
G.F. Bastin ◽  
H.J.M. Heijligers

Among the ultra-light elements B, C, N, and O nitrogen is the most difficult element to deal with in the electron probe microanalyzer. This is mainly caused by the severe absorption that N-Kα radiation suffers in carbon which is abundantly present in the detection system (lead-stearate crystal, carbonaceous counter window). As a result the peak-to-background ratios for N-Kα measured with a conventional lead-stearate crystal can attain values well below unity in many binary nitrides . An additional complication can be caused by the presence of interfering higher-order reflections from the metal partner in the nitride specimen; notorious examples are elements such as Zr and Nb. In nitrides containing these elements is is virtually impossible to carry out an accurate background subtraction which becomes increasingly important with lower and lower peak-to-background ratios. The use of a synthetic multilayer crystal such as W/Si (2d-spacing 59.8 Å) can bring significant improvements in terms of both higher peak count rates as well as a strong suppression of higher-order reflections.


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