Parallel direct numerical simulation and analysis of turbulent Rayleigh-Benard convection at moderate Rayleigh numbers using an efficient algorithm
Küçük Resim Yok
Tarih
2020
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Pergamon-Elsevier Science Ltd
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Direct numerical simulation of turbulent Rayleigh-Benard convection up to Rayleigh number 10(8) is performed using a fully-implicit, non-dissipative, discrete kinetic energy-conserving algorithm and a parallel flow solver based on it. The algorithm is especially suitable for simulating low-Mach number, variable density/viscosity, transitional and turbulent flows with or without heat transfer. Furthermore, since it does not rely on the Boussinesq assumption, large temperature differences and high Rayleigh numbers can be handled without loss of accuracy, unlike the pure incompressible ones. It is first shown that the algorithm is able to predict the evolution of thermally-driven instability to turbulent regime and all the characteristics of turbulent convection accurately, using low- and high-order turbulent statistics and various secondary diagnostics derived. Then, effects of increasing Rayleigh numbers on the development of the instability are analyzed in detail. Additionally, Nusselt-Rayleigh scaling properties are studied and a scaling relation is provided. Results show that Rayleigh-Benard convection at relatively high Rayleigh numbers, corresponding to a boundary layer-dominated regime and little beyond it to a bulk-dominated regime, is characterized by weakening thermal fluctuations, thinning thermal boundary layers, increasing vertical velocity fluctuations and decreasing skewness. It is also observed that the turbulent heat flux dominates the heat transfer. Finally, the corresponding Nusselt-Rayleigh scaling relation is predicted as Nu = 0.132Ra(0.297). (C) 2020 Elsevier Ltd. All rights reserved.
Açıklama
Anahtar Kelimeler
Dns, Rayleigh-Benard Convection, Rayleigh Number, Nu-Ra Scaling, Parallel Solver, Low-Mach Number, Flow, Temperature, Resolution, Layer
Kaynak
Computers & Fluids
WoS Q Değeri
Q2
Scopus Q Değeri
Q1
Cilt
213
