A near-wall strategy for buoyancy-affected turbulent flows using stabilized FEM with applications to indoor air flow simulation

Knopp, Tobias; Lube, Gert; Gritzki, Ralf; Rösler, Markus

doi:10.1016/j.cma.2004.10.003

Cited by 14 publications

(13 citation statements)

References 12 publications

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“…Piecewise linear elements (r = 1) for all unknowns together with all stabilization techniques (as described in this section) are used. The results are compared with experimental data in [30] and with numerical results using the k-ε model with wall functions, see [13]. Figure 6 shows the boundary layer profiles for the vertical velocity component u 2 /u 0 (with reference velocity u 0 = 0.9692 m s −1 ) near the hot left wall at y/L = 0.2 and 0.5 for the k-ε--f model, which are in reasonable agreement with the experimental data.…”

Section: Application To a Non-isothermal Benchmark Problemmentioning

confidence: 98%

“…with the turbulent time scale T = max min k ε ; r C √ 6 |S(u)| ; 6 (13) and the constants as in Table I. The turbulence length scale in (12) is given by…”

Section: G Lube Et Almentioning

confidence: 99%

“…An eddy viscosity assumption for turbulent effects is considered e = + t , a e = a + t Pr t (7) with Pr t = 0.9 for air. For the turbulent viscosity t , we will use either the standard k-model with the turbulent kinetic energy k and the turbulent dissipation rate , together with wall functions [7,9,13] or, as an improved variant, the k-ε-v 2 -f model with the additionally modelled wallnormal velocity fluctuation v 2 and the elliptic relaxation f of Durbin and Petterson Reif [4]. More precisely, we will consider the 'code-friendly' -f version of the k-ε-v 2 -f model [5,6], the so-called k-ε--f model with the additional variable = v 2 /k with the turbulent viscosities…”

Section: Introductionmentioning

confidence: 99%

“…For the standard k-ε model, an improved wall function method is employed at the Dirichlet walls [12,13], where modified boundary conditions are used prescribing the wall-shear stress s w and the heat fluxq:…”

mentioning

confidence: 99%

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Stabilized finite element methods to predict ventilation efficiency and thermal comfort in buildings

Lube

Knopp²,

Rapin

et al. 2008

Numerical Methods in Fluids

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SUMMARYThe non-isothermal, incompressible Navier-Stokes equations with Boussinesq approximation are considered as a model of turbulent indoor air flows. The transient calculation is based on the Reynolds-averaged Navier-Stokes problem using the k/ε-turbulence model or improved variants such as the v 2 − f model. The model is first discretized in time using backward-differencing schemes and then linearized using a Newton-type method per time step with emphasis on the proper calculation of (non-negative) turbulence quantities. The resulting auxiliary problems of Oseen type and of advection-diffusion-reaction type are solved using stabilized finite element method of residual type. Here we summarize some of our recent analytical results for higher-order methods and shock-capturing techniques. The numerical solution to the model in boundary layer regions is obtained using either adaptive wall functions if the k-ε model is used or a hybrid mesh with anisotropic refinement if the v 2 − f model is applied. Besides the standard flow quantities, it is possible to calculate quantities such as the age of the air. Such quantities are used to develop criteria for the evaluation of the efficiency of air exchange in a room. The quality of the numerical simulations is demonstrated for typical benchmark problems.

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Section: Application To a Non-isothermal Benchmark Problemmentioning

confidence: 98%

“…with the turbulent time scale T = max min k ε ; r C √ 6 |S(u)| ; 6 (13) and the constants as in Table I. The turbulence length scale in (12) is given by…”

Section: G Lube Et Almentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Stabilized finite element methods to predict ventilation efficiency and thermal comfort in buildings

Lube

Knopp²,

Rapin

et al. 2008

Numerical Methods in Fluids

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“…Der für die Strömungssimulation eingesetzte Forschungscode ParallelNS [2], [3] Weitere, ausführliche Informationen zu den kompletten zugrunde liegenden mathematischen Modellen finden sich in [1], [2], [3] und [4].…”

Section: Mathematisches Modell Und Randbedingungenunclassified

Vorhersage und Analyse natürlicher Lüftungsvorgänge

Gritzki¹,

Rösler²,

Richter³

2007

Bauphysik

Self Cite

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Die rechnerische Vorhersage natürlicher Lüftungsvorgänge in Gebäuden gestaltet sich aufgrund der Problematik der Randbedingungen und der instationären Natur des Vorganges oft schwierig. Hinzu kommt, daß der reine Lüftungsvorgang lediglich eine Teil information liefert, wenn beispielsweise Nachtlüftungen und die damit einhergehende Entwärmung untersucht werden müssen. Unter Nutzung der Möglichkeiten einer speziellen Finite‐Elemente‐Methode (FEM) lassen sich Randbedingungsformulierungen finden, die für die Berechnung natürlicher Lüftungsvorgänge geeignet sind. Weiterhin werden Möglichkeiten und Kriterien vorgestellt, instationäre Lüftungsvorgänge unter hygienischen und energetischen Gesichtspunkten zu analysieren. Der energetische Aspekt lässt sich besonders herausarbeiten, wenn man Raumluftströmungsberechnung und thermische Gebäudesimulation geeignet kombiniert.

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Ein Modell zur hygrisch‐thermischen Gebäudesimulation mit Hilfe der Kopplung von Zonen‐ und Feldmodell

Perschk

Meinhold

2007

Bauphysik

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A near-wall strategy for buoyancy-affected turbulent flows using stabilized FEM with applications to indoor air flow simulation

Cited by 14 publications

References 12 publications

Stabilized finite element methods to predict ventilation efficiency and thermal comfort in buildings

Stabilized finite element methods to predict ventilation efficiency and thermal comfort in buildings

Vorhersage und Analyse natürlicher Lüftungsvorgänge

Ein Modell zur hygrisch‐thermischen Gebäudesimulation mit Hilfe der Kopplung von Zonen‐ und Feldmodell

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