Tae Seon Park

Development of a near-wall turbulence model and application to jet impingement heat transfer

Abstract A near-wall turbulence model was developed and applied to heat and fluid flows for an impinging jet flow. The k – e – f μ model was modified for predictions in strongly strained turbulent flows. To derive a realizable eddy viscosity, the f μ 2 function was newly formulated. The near-wall effect and the anisotropic production were reflected in the e -equation. The model performance was validated by the relevant experimental data. The predicted results were compared with those by the k – e model and by the k – e – v 2 model. The application to jet impingement heat transfer revealed that the present numerical predictions of wall heat transfer show good agreement with the experimental data in the stagnation region. The influence of the Reynolds number on the stagnation Nusselt number was investigated. The model performance was shown to be generally satisfactory.

Development of a nonlinear near-wall turbulence model for turbulent flow and heat transfer

Abstract A new nonlinear near-wall turbulence model is developed on the basis of realizability constraints to predict turbulent flow and heat transfer in strongly nonequilibrium flows. The linear k–e–fμ model of Park and Sung (Fluid Dyn. Res., 20 (1997) 97) is extended to a nonlinear formulation. The stress–strain relationship is derived from the Cayley–Hamilton theorem in a homogeneous flow. The ratio of production to dissipation (Pk/e) is employed to solve an algebraic equation of the strain dependent coefficients. A near-wall treatment is dealt with by reproducing the model coefficients from a modified strain variable. An improved explicit heat flux model is proposed with the aid of Cayley–Hamilton theorem, which includes the quadratic effects of flow deformations. The near-wall asymptotic behavior is incorporated by modifying the fλ function. Emphasis is placed on the model performance on the truncated strain terms. The model performance is shown to be generally satisfactory.

Local convective mass transfer on circular cylinder with transverse annular fins in crossflow

Abstract An experimental study was made of local mass transfer from a circular cylinder, which is situated between two annular fins in a crossflow. Low turbulence-intensity wind tunnel experiments were conducted over moderate Reynolds numbers, 33 000

A new low-Reynolds-number k-ε-fμ model for predictions involving multiple surfaces

A new k--fμ turbulence model is proposed, in which the near-wall effect without reference to distance and the non-equilibrium effect are incorporated. In this model, the non-local near-wall effect in a general coordinate system is taken into account by the fμ equation, and the local anisotropy in strongly strained turbulent flows in introduced in the equation. The near-wall characteristics of the present model are ascertained from the DNS data. Also, the validation is explored to separate and reattaching flows. The backward-facing step flow is selected for benchmark test of the present model and the response of the model to flows involving complex surfaces is assessed. The predictions of the present model are checked with the existing measurements. The model performance is shown to be generally satisfactory.

Application of a near-wall turbulence model to the flows over a step with inclined wall

A nonlinear low-Reynolds-number κ-ϵ model of Park and Sung (1995) was extended to predict the flows over a step with inclined wall, where a boundary-layer flow without separation and a separated and reattaching flow coexist. For a better prediction of the flows, a slight modification was made on the function of wall damping μμ and the model constant Cϵ1 in the ϵ-equation. The model performance was validated by comparing the model predictions with the experiment. It was shown that the flows over a step with inclined wall are simulated successfully with the present model.