Finite-volume models with implicit subgrid-scale parameterization for the differentially heated rotating annulus
S. Borchert, U. Achatz, S. Remmler, S. Hickel, U. Harlander, M. Vincze, K.D. Alexandrov, F. Rieper, T. Heppelmann, S.I. Dolaptchiev (2014)
Meteorologische Zeitschrift 23: 561-580. doi: 10.1127/metz/2014/0548
The differentially heated rotating annulus is a classical experiment for the investigation of baroclinic flows and can be regarded as a strongly simplified laboratory model of the atmosphere in mid-latitudes. Data of this experiment, measured at the BTU Cottbus-Senftenberg, are used to validate two numerical finite-volume models (INCA and cylFloit) which differ basically in their grid structure.
Evolution of length scales and statistics of Richtmyer-Meshkov instability from direct numerical simulations
V.K. Tritschler, M. Zubel, S. Hickel, N.A. Adams (2014)
Physical Review E 90: 063001. doi: 10.1103/PhysRevE.90.063001
In this study we present direct numerical simulation results of the Richtmyer-Meshkov instability (RMI) initiated by Ma = 1.05, Ma = 1.2, and Ma = 1.5 shock waves interacting with a perturbed planar interface between air and SF6. At the lowest shock Mach number the fluids slowly mix due to viscous diffusion, whereas at the highest shock Mach number the mixing zone becomes turbulent.
Cut-element based immersed boundary method for moving geometries in compressible liquid flows with cavitation
F. Örley, V. Pasquariello, S. Hickel, N.A. Adams (2015)
Journal of Computational Physics 283: 1-22. doi: 10.1016/j.jcp.2014.11.028
The conservative immersed interface method for representing complex immersed solid boundaries or phase interfaces on Cartesian grids is improved and extended to allow for the simulation of weakly compressible fluid flows through moving geometries. We demonstrate that an approximation of moving interfaces by a level-set field results in unphysical oscillations in the vicinity of sharp corners when dealing with weakly compressible fluids such as water. By introducing an exact reconstruction of the cut-cell properties directly based on a surface triangulation of the immersed boundary, we are able to recover the correct flow evolution free of numerical artifacts.
Subgrid-scale modeling for implicit Large Eddy Simulation of compressible flows and shock turbulence interaction
S. Hickel, C.P. Egerer, J. Larsson (2014)
Physics of Fluids 26: 106101. doi: 10.1063/1.4898641
LES of Temporally Evolving Turbulent Cavitating Shear Layers
C.P. Egerer, S. Hickel, S.J. Schmidt, N.A. Adams (2014)
High Performance Computing in Science and Engineering ’14: 367-378 doi: 10.1007/978-3-319-10810-0_25
We present LES results of temporally evolving cavitating shear layers. Cavitation is modeled by a homogeneous equilibrium mixture model whereas the effect of subgrid-scale turbulence is accounted for by the Adaptive Local Deconvolution Method (ALDM). We quantitatively compare LES results with experimental data available in the literature.
On the construction of a direct numerical simulation of a breaking inertia-gravity wave in the upper-mesosphere
M.D. Fruman, S. Remmler, U. Achatz, S. Hickel (2014)
Journal of Geophysical Research 119: 11613-11640. doi: 10.1002/2014JD022046
A systematic approach to the direct numerical simulation (DNS) of breaking upper mesospheric inertia-gravity waves of amplitude close to or above the threshold for static instability is presented. Normal mode or singular vector analysis applied in a frame of reference moving with the phase velocity of the wave (in which the wave is a steady solution) is used to determine the most likely scale and structure of the primary instability
Spectral eddy viscosity of stratified turbulence
S. Remmler, S. Hickel (2014)
Journal of Fluid Mechanics 755, R6. doi: 10.1017/jfm.2014.423
The spectral eddy viscosity (SEV) concept is a handy tool for the derivation of large-eddy simulation (LES) turbulence models and for the evaluation of their performance in predicting the spectral energy transfer. We compute this quantity by filtering and truncating fully resolved turbulence data from direct numerical simulations (DNS) of neutrally and stably stratified homogeneous turbulence. The results qualitatively confirm the plateau–cusp shape, which is often assumed to be universal, but show a strong dependence on the test filter size. Increasing stable stratification not only breaks the isotropy of the SEV but also modifies its basic shape, which poses a great challenge for implicit and explicit LES methods. We find indications that for stably stratified turbulence it is necessary to use different subgrid-scale (SGS) models for the horizontal and vertical velocity components. Our data disprove models that assume a constant positive effective turbulent Prandtl number.
On the Richtmyer-Meshkov instability evolving from a deterministic multimode planar interface
V.K. Tritschler, B. Olson, S. Lele, S. Hickel, X.Y. Hu, N.A. Adams (2014)
Journal of Fluid Mechanics 755, 429-462. doi: 10.1017/jfm.2014.436
We investigate the shock-induced turbulent mixing between a light and a heavy gas, where a Richtmyer–Meshkov instability (RMI) is initiated by a shock wave with Mach number Ma = 1.5. The prescribed initial conditions define a deterministic multimode interface perturbation between the gases, which can be imposed exactly for different simulation codes and resolutions to allow for quantitative comparison. Well-resolved large-eddy simulations are performed using two different and independently developed numerical methods with the objective of assessing turbulence structures, prediction uncertainties and convergence behaviour.
Large-eddy simulation of turbulent cavitating flow in a micro channel
C.P. Egerer, S. Hickel, S.J. Schmidt, N.A. Adams (2014)
Physics of Fluids 26, 085102. doi: 10.1063/1.4891325
Large-eddy simulations (LES) of cavitating flow of a Diesel-fuel-like fluid in a generic throttle geometry are presented. Two-phase regions are modeled by a parameter-free thermodynamic equilibrium mixture model, and compressibility of the liquid and the liquid-vapor mixture is taken into account. The Adaptive Local Deconvolution Method (ALDM), adapted for cavitating flows, is employed for discretizing the convective terms of the Navier-Stokes equations for the homogeneous mixture.
Large-eddy simulation of a pseudo-shock system in a Laval nozzle
J.F. Quaatz, M. Giglmaier, S. Hickel, N.A. Adams (2014)
International Journal of Heat and Fluid Flow 49: 108-115. doi: 10.1016/j.ijheatfluidflow.2014.05.006
Well-resolved Large-Eddy Simulations (LES) of a pseudo-shock system in the divergent part of a Laval nozzle with rectangular cross section are conducted and compared with experimental results. The LES matches the parameter set of a reference experiment. Details of the experiment, such as planar side walls, are taken into account, all wall boundary layers are well-resolved and no wall model is used.
Large-eddy simulation of passive shock-wave/boundary-layer interaction control
V. Pasquariello, M. Grilli, S. Hickel, N.A. Adams (2014)
International Journal of Heat and Fluid Flow 49: 116-127. doi: 10.1016/j.ijheatfluidflow.2014.04.005
We investigate a passive flow-control technique for the interaction of an oblique shock generated by an 8.8° wedge with a turbulent boundary-layer at a free-stream Mach number of Ma∞ = 2.3 and a Reynolds number based on the incoming boundary-layer thickness of Reδ = 60 500 by means of large-eddy simulation (LES).
On the application of WKB theory for the simulation of the weakly nonlinear dynamics of gravity waves
J. Muraschko, M.D. Fruman, U. Achatz, S. Hickel, Y. Toledo (2015)
Quarterly Journal of the Royal Meteorological Society 141: 676-697. doi: 10.1002/qj.2381
The dynamics of internal gravity waves is modelled using Wentzel–Kramer–Brillouin (WKB) theory in position–wave number phase space. A transport equation for the phase-space wave-action density is derived for describing one-dimensional wave fields in a background with height-dependent stratification and height- and time-dependent horizontal-mean horizontal wind, where the mean wind is coupled to the waves through the divergence of the mean vertical flux of horizontal momentum associated with the waves.
Quantification of initial-data uncertainty on a shock-accelerated gas cylinder
V.K. Tritschler, A. Avdonin, S. Hickel, X.Y. Hu, N.A. Adams (2014)
Physics of Fluids 26: 026101. doi: 10.1063/1.4865756
We quantify initial-data uncertainties on a shock accelerated heavy-gas cylinder by two-dimensional well-resolved direct numerical simulations. A high-resolution compressible multicomponent flow simulation model is coupled with a polynomial chaos expansion to propagate the initial-data uncertainties to the output quantities of interest.
Numerical modeling of separated flows at moderate Reynolds numbers appropriate for turbine blades and unmanned aero vehicles
G. Castiglioni, J.A. Domaradzki, V. Pasquariello, S. Hickel, M. Grilli (2014)
International Journal of Heat and Fluid Flow 49: 92-99. doi: 10.1016/j.ijheatfluidflow.2014.02.003
Flows over airfoils and blades in rotating machinery, for unmanned and micro-aerial vehicles, wind turbines, and propellers consist of a laminar boundary layer near the leading edge that is often followed by a laminar separation bubble and transition to turbulence further downstream. Typical RANS turbulence models are inadequate for such flows. Direct numerical simulation (DNS) is the most reliable, but is also the most computationally expensive alternative. This work assesses the capability of Immersed Boundary (IB) methods and Large Eddy Simulations (LES) to reduce the computational requirements for such flows and still provide high quality results.
On the Kolmogorov inertial subrange developing from Richtmyer-Meshkov instability
V.K. Tritschler, S. Hickel, X.Y. Hu, N.A. Adams (2013)
Physics of Fluids 25: 071701. doi: 10.1063/1.4813608
We present results of well-resolved direct numerical simulations (DNS) of the turbulent flowevolving from Richtmyer-Meshkov instability (RMI) in a shock-tube with square cross section. The RMI occurs at the interface between a mixture of O2 and N2 (light gas) and SF6 and acetone (heavy gas).
Numerical simulation of a Richtmyer-Meshkov instability with an adaptive central-upwind 6th-order WENO scheme
V.K. Tritschler, X.Y. Hu, S. Hickel, N.A. Adams (2013)
Physica Scripta 2013: 014016. doi: 10.1088/0031-8949/2013/T155/014016
Two-dimensional simulations of the single-mode Richtmyer–Meshkov instability (RMI) are conducted and compared to experimental results of Jacobs and Krivets (2005).