A simple cartesian model of boundary layer flow over topography

Mason, P. J.; Sykes, R. I.

doi:10.1016/0021-9991(78)90034-7

Cited by 21 publications

(12 citation statements)

References 11 publications

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“…Finally, we plan to add an option to use viscous topography for urban LES and complex terrain after Mason and Sykes (1978), where topography in PALM will be represented by grid volumes with infinite viscosity instead of using solid elements. Unlike the present implementation, where grid volumes can either be set to topography or fluid, sloping surfaces will be better represented by adjusting the viscosity of the respective grid volumes.…”

Section: Current and Future Developmentsmentioning

confidence: 99%

The Parallelized Large-Eddy Simulation Model (PALM) version 4.0 for atmospheric and oceanic flows: model formulation, recent developments, and future perspectives

et al. 2015

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Abstract. In this paper we present the current version of the Parallelized Large-Eddy Simulation Model (PALM) whose core has been developed at the Institute of Meteorology and Climatology at Leibniz Universität Hannover (Germany). PALM is a Fortran 95-based code with some Fortran 2003 extensions and has been applied for the simulation of a variety of atmospheric and oceanic boundary layers for more than 15 years. PALM is optimized for use on massively parallel computer architectures and was recently ported to general-purpose graphics processing units. In the present paper we give a detailed description of the current version of the model and its features, such as an embedded Lagrangian cloud model and the possibility to use Cartesian topography. Moreover, we discuss recent model developments and future perspectives for LES applications.

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Section: Current and Future Developmentsmentioning

confidence: 99%

The Parallelized Large-Eddy Simulation Model (PALM) version 4.0 for atmospheric and oceanic flows: model formulation, recent developments, and future perspectives

et al. 2015

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“…To improve the crude steplike boundary representation that is typical for Cartesian models, we use the method of viscous topography first suggested by Mason and Sykes (1978). For ease of reference this method will be briefly outlined here.…”

Section: Treatment Of Orographymentioning

confidence: 99%

A new large-eddy simulation model for simulating air flow and warm clouds above highly complex terrain. Part I: The dry model

Reinert

Wirth

Eichhorn

et al. 2007

Boundary-Layer Meteorol

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This paper presents the dry version of a new large-eddy simulation (LES) model, which is designed to simulate air flow and clouds above highly complex terrain. The model is three-dimensional and nonhydrostatic, and the governing equations are sound filtered by use of the anelastic approximation. A fractional step method is applied to solve the equations on a staggered Cartesian grid. Arbitrarily steep and complex orography can be accounted for through the method of viscous topography. The dynamical model core is validated by comparing the results for a spreading density current against a benchmark solution. The model accuracy is further assessed through the simulation of turbulent flow across a quasi two-dimensional ridge. The results are compared with wind-tunnel data. The method of viscous topography is not restricted to moderately sloped terrain. Compared to models using curvilinear grids, it allows this model to be applied to a much wider range of flows. This is illustrated through the simulation of an atmospheric boundary-layer flow over a surface mounted cube. The results show that the dry model version is able to accurately represent the complex flow in the vicinity of three-dimensional obstacles. It is concluded that the method of viscous topography was successfully implemented into a micrometeorological LES model. As will be shown in Part II, this allows the detailed study of clouds in highly complex terrain.

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“…Dirichlet boundary conditions cannot be used on the bottom boundary because the terrain is the source of the pressure disturbance, which is not necessarily constant along the surface. Instead, it will be assumed that a&H -=O, an (Neumann boundary conditions) which also was used in the simulations by Mason and Sykes (1978). In the simulations reported in this paper, it is assumed that the pressure perturbation is not zero on the downwind boundary; therefore, Neumann boundary conditions will be used there as well.…”

Section: Pressure Residualmentioning

confidence: 99%

“…For flow over terrain, Pielke (1975, 1977) used scales large enough so that the hydrostatic assumption was valid, but then many of the small-scale flow patterns were unresolved. On the other hand, Taylor (1977) and Mason and Sykes (1978) have done considerable modeling of flow over smaller symmetric terrain features by using nonhydrostatic models. It is of interest to examine the error incurred by assuming the hydrostatic approximation and the resulting effects on the flow field in complex terrain.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of an alternative method for numerically modeling nonhydrostatic flows over irregular terrain

Fast

Takle

1988

Boundary-Layer Meteorol

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Modeling nonhydrostatic atmospheric flow requires the solution of the vertical equation of motion and a prognostic or diagnostic equation for pressure. If the nonhydrostatic components of the flow are relatively small, they can be approximated and incorporated into a purely hydrostatic model, which usually is conceptually simpler and computationally more efficient. A method to do this for a linear model of local thermally-induced circulations is further developed and adapted to a non-linear numerical tnodel of the neutral atmospheric boundary layer. A hydrostatic model and the quasinonhydrostatic version were used to simulate neutral flow over simple terrain features. One set of observations taken over a simple change in roughness and another set taken over a change in both roughness and terrain were simulated by both models to assess the capabilities of the quasinonhydrostatic technique.It is found that (as expected) the pressure deviation from the hydrostatic state is negligible for the roughness change, but it is an important aspect of neutral flow over terrain. Thus, for flow encountering a simple roughness change, the hydrostatic approximation is good, even for small horizontal scales. However, the quasi-nonhydrostatic model qualitatively produces the features in the observations for flow over a terrain change that the hydrostatic model cannot produce.

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A simple cartesian model of boundary layer flow over topography

Cited by 21 publications

References 11 publications

The Parallelized Large-Eddy Simulation Model (PALM) version 4.0 for atmospheric and oceanic flows: model formulation, recent developments, and future perspectives

The Parallelized Large-Eddy Simulation Model (PALM) version 4.0 for atmospheric and oceanic flows: model formulation, recent developments, and future perspectives

A new large-eddy simulation model for simulating air flow and warm clouds above highly complex terrain. Part I: The dry model

Evaluation of an alternative method for numerically modeling nonhydrostatic flows over irregular terrain

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