共查询到20条相似文献,搜索用时 46 毫秒
1.
Felix Rieper 《Journal of computational physics》2011,230(13):5263-5287
We present a low-Mach number fix for Roe’s approximate Riemann solver (LMRoe). As the Mach number Ma tends to zero, solutions to the Euler equations converge to solutions of the incompressible equations. Yet, standard upwind schemes do not reproduce this convergence: the artificial viscosity grows like 1/Ma, leading to a loss of accuracy as Ma → 0. With a discrete asymptotic analysis of the Roe scheme we identify the responsible term: the jump in the normal velocity component ΔU of the Riemann problem. The remedy consists of reducing this term by one order of magnitude in terms of the Mach number. This is achieved by simply multiplying ΔU with the local Mach number. With an asymptotic analysis it is shown that all discrepancies between continuous and discrete asymptotics disappear, while, at the same time, checkerboard modes are suppressed. Low Mach number test cases show, first, that the accuracy of LMRoe is independent of the Mach number, second, that the solution converges to the incompressible limit for Ma → 0 on a fixed mesh and, finally, that the new scheme does not produce pressure checkerboard modes. High speed test cases demonstrate the fall back of the new scheme to the classical Roe scheme at moderate and high Mach numbers. 相似文献
2.
Heat transfer in lattice BGK modeled fluid 总被引:1,自引:0,他引:1
The thermal lattice BGK model is a recently suggested numerical tool aiming at solving problems of thermohydrodynamics. The quality of the lattice BGK simulation is checked in this paper by calculating temperature profiles in the Couette flow under different Eckert and Mach numbers. A revised lower order model is proposed to improve the accuracy and the higher order model is proved to be advantageous in this respect, especially in the flow regime with a higher Mach number. 相似文献
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In this Letter, we present an analytical study of a high-order acoustic wave equation in one dimension, and reformulate a previously given equation in terms of an expansion of the acoustic Mach number. We search for non-trivial traveling wave solutions to this equation, and also discuss the accuracy of acoustic wave equations in terms of the range of Mach numbers for which they are valid. 相似文献
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Lattice Boltzmann (LB) modeling of high-speed compressible flows has long been attempted by various authors. One common weakness of most of previous models is the instability problem when the Mach number of the flow is large. In this paper we present a finite-difference LB model, which works for flows with flexible ratios of specific
heats and a wide range of Mach number, from $0$ to 30 or higher. Besides the discrete-velocity-model by Watari [Physica A 382 (2007) 502], a modified Lax--Wendroff finite difference
scheme and an artificial viscosity are introduced. The combination of the finite-difference scheme and the adding of artificial viscosity must find a balance of numerical stability versus
accuracy. The proposed model is validated by recovering results of
some well-known benchmark tests: shock tubes and shock reflections.
The new model may be used to track shock waves and/or to study the
non-equilibrium procedure in the transition between the regular and
Mach reflections of shock waves, etc. 相似文献
7.
A generalized hydrodynamic theory of shock wave structures is presented for rigid diatomic gases. The theory yields shock solutions for all Mach numbers. The accuracy of the theory is examined for nitrogen gas as an example. Excellent agreement with experiment is obtained for the inverse shock widths for the entire range of Mach number studied by experiment. The comparison made shows that we are now in possession of a successful continuum theory of shock waves in molecular gases for all Mach numbers. 相似文献
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Babak Hejazialhosseini Diego Rossinelli Michael Bergdorf Petros Koumoutsakos 《Journal of computational physics》2010,229(22):8364-8383
We present a space–time adaptive solver for single- and multi-phase compressible flows that couples average interpolating wavelets with high-order finite volume schemes. The solver introduces the concept of wavelet blocks, handles large jumps in resolution and employs local time-stepping for efficient time integration. We demonstrate that the inherently sequential wavelet-based adaptivity can be implemented efficiently in multicore computer architectures using task-based parallelism and introducing the concept of wavelet blocks. We validate our computational method on a number of benchmark problems and we present simulations of shock-bubble interaction at different Mach numbers, demonstrating the accuracy and computational performance of the method. 相似文献
9.
F. Bassi C. De Bartolo R. Hartmann A. Nigro 《Journal of computational physics》2009,228(11):3996-4011
In this work we extend the high-order discontinuous Galerkin (DG) finite element method to inviscid low Mach number flows. The method here presented is designed to improve the accuracy and efficiency of the solution at low Mach numbers using both explicit and implicit schemes for the temporal discretization of the compressible Euler equations. The algorithm is based on a classical preconditioning technique that in general entails modifying both the instationary term of the governing equations and the dissipative term of the numerical flux function (full preconditioning approach). In the paper we show that full preconditioning is beneficial for explicit time integration while the implicit scheme turns out to be efficient and accurate using just the modified numerical flux function. Thus the implicit scheme could also be used for time accurate computations. The performance of the method is demonstrated by solving an inviscid flow past a NACA0012 airfoil at different low Mach numbers using various degrees of polynomial approximations. Computations with and without preconditioning are performed on different grid topologies to analyze the influence of the spatial discretization on the accuracy of the DG solutions at low Mach numbers. 相似文献
10.
A kinetic equation with a relaxation time model for wave-particle collisions is considered. Similarly to the BGK-model of
gas dynamics, it involves a projection onto the set of equilibrium distributions, nonlinearly dependent on the moments of
the distribution function. Under a diffusive and low Mach number scaling the macroscopic limit is a generalization of the
incompressible Navier-Stokes equations, where the momentum equations are coupled to a diffusive equation for an energy distribution
function. By a moment approximation, this system can be related to a low Mach number model of fluid mechanics, which already
appeared in the literature. Finally, for a linearized version corresponding to Stokes flow an existence result for initial
value problems is proved. 相似文献
11.
Huajun Zhu Xiaogang Deng Meiliang Mao Huayong Liu & Guohua Tu 《advances in applied mathematics and mechanics.》2016,8(4):670-692
We compare in this paper the properties of Osher flux with O-variant and
P-variant (Osher-O flux and Osher-P flux) in finite volume methods for the two-dimensional
Euler equations and propose an entropy fix technique to improve their
robustness. We consider both first-order and second-order reconstructions. For inviscid
hypersonic flow past a circular cylinder, we observe different problems for different
schemes: a first-order Osher-O scheme on quadrangular grids yields a carbuncle
shock, while a first-order Osher-P scheme results in a dislocation shock for high Mach
number cases. In addition, a second-order Osher scheme can also yield a carbuncle
shock or be unstable. To improve the robustness of these schemes we propose an entropy
fix technique, and then present numerical results to show the effectiveness of
the proposed method. In addition, the influence of grid aspects ratio, relative shock
position to the grid and Mach number on shock stability are tested. Viscous heating
problem and double Mach reflection problem are simulated to test the influence of the
entropy fix on contact resolution and boundary layer resolution. 相似文献
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Dr Julian B. Barbour 《Contemporary Physics》2013,54(3):321-322
Ernst Mach (1838-1916) is chiefly famous on two counts: for his brilliant experimental work on shock waves (in recognition of which the Mach number is named after him) and for his numerous critical historical studies of the development of physics. It was through these studies that Mach became an extremely influential and controversial figure in the physics of the twentieth century. This explains why the present work, a translation into English of his Die Principien der Wärmelehre, which was first published in 1896, now appears as Volume 17 of the Vienna Circle Collection published by Reidel. (The Vienna Circle was a discussion group of philosophically interested scholars who met weekly from 1925 to 1936 at the University of Vienna. Mach was regarded as one of their precursors.) 相似文献
16.
High sampling-rate measurement of turbulence velocity fluctuations in Mach 1.8 Laval jet using interferometric Rayleigh scattering
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Interferometric Rayleigh scattering diagnostic technique for the time-resolved measurement of flow velocity is studied. Theoretically, this systematic velocity-measured accuracy can reach up to 1.23 m/s. Measurement accuracy is then evaluated by comparing with hot wire anemometry results. Moreover, the distributions of velocity and turbulence intensity in a supersonic free jet from a Laval nozzle with a Mach number of 1.8 are also obtained quantitatively. The sampling rate in this measurement is determined to be approximately 10 k Hz. 相似文献
17.
Studies on the properties of flow-induced oscillation and sound radiation in streamlined protuberant special cavities 总被引:1,自引:0,他引:1
I.IntroductionAsanuidpassingthroughthecavityatcertainflowrate,themediuminthemouthandthccavityisoscillatingandsoundisradiated.Noton1ystochasticturbu1encenoiscispossi-blyproducedbutsinglefrequencysoundofspecia1lydesignatedpitchisalsoproduced.Andthusthespcctrumofthcradiatedsoundisshownascontinuousspectrumandcharacteristiclinespcctrum.Inthiscascwcmaycallitflow-inducedosci1lation.Flow-inducedoscillationandsoundradiationcanbeproducedasafluid(waterorgas)passingthroughthecavitybysinkingcavityunderint… 相似文献
18.
D. A. Vnuchkov V. I. Zvegintsev D. G. Nalivaichenko 《Thermophysics and Aeromechanics》2014,21(2):171-178
Results of an experimental study of a cylindrical air inlet designed for high flight speeds on the basis of plane flows are reported. For an air inlet intended for Mach number M = 4, the flow-rate characteristics at M = 2.85, 3.83, and 4.95 for angles of attack ranging from 0 to 9 degrees have been measured. The results of tests have shown that at free-stream Mach number M = 3.83, close to the design Mach number, the mass rate of the air flow captured by the air inlet was 96 % of its design value, and this rate increased to 99 % as the Mach number was increased to 4.95. At a lower, in comparison with the design value, free-stream Mach number, M = 2.85, the mass rate of the air flow captured by the inlet installed under zero angle of attack has decreased to 68 %. For all the examined Mach numbers, an increase in the angle of attack from 0 to 9 degrees resulted in an 8–14 % decrease of the mass rate of inlet-captured air flow. For comparison, numerical calculation of the air-inlet flow at Mach number M = 3.83 was performed. The obtained data were found to be in a qualitative agreement with experimental data. 相似文献
19.
Preconditioned characteristic boundary conditions (BCs) are implemented at artificial boundaries for the solution of the two- and three-dimensional preconditioned Euler equations at low Mach number flows. The preconditioned compatibility equations and the corresponding characteristic variables (or the Riemann invariants) based on the characteristic forms of preconditioned Euler equations are mathematically derived for three preconditioners proposed by Eriksson, Choi and Merkle, and Turkel. A cell-centered finite volume Roe’s method is used for the discretization of the preconditioned system of equations on unstructured meshes. The accuracy and performance of the preconditioned characteristic BCs applied at artificial boundaries are evaluated in comparison with the non-preconditioned characteristic BCs and the simplified BCs in computing steady low Mach number flows. The two-dimensional flow over the NACA0012 airfoil and three-dimensional flow over the hemispherical headform are computed and the results are obtained for different conditions and compared with the available numerical and experimental data. The sensitivity of the solution to the size of computational domain and the variation of the angle of attack for each type of BCs is also examined. Indications are that the preconditioned characteristic BCs implemented in the preconditioned system of Euler equations greatly enhance the convergence rate of the solution of low Mach number flows compared to the other two types of BCs. 相似文献
20.
D. Mazzoni 《Journal of sound and vibration》2003,264(4):951-971
The aim of this study was to present a deterministic model for approximating the vibrations and the acoustic pressure radiated when a thin elastic plate is immersed in a low Mach number flow of fluid. As a prelude to this study, a classical random model based on a wavevector integration technique was used. In the case of a low Mach number turbulent flow, the numerical study showed that the subconvective region of the turbulent excitation power spectrum contributes significantly to the response of the panel. A deterministic approximate model was developed, based on this behaviour of the system. 相似文献