PSI - Issue 27

Aldias Bahatmaka et al. / Procedia Structural Integrity 27 (2020) 6–13 Bahatmaka et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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3. Validation of numerical approach against the experimental 3.1. The boundary conditions and turbulence models

Prediction using a numerical approach for wind loads analysis should be considered to validate against the experimental. The numerical approach is growing popular with cost-effectiveness. Reducing time, cost production process, a numerical method is being rapidly on the development. Since the development of the mathematical approach should have the improvement of design and analysis as an important calculation in engineering design. Before the numerical computation, the first step that should be considered is to determine the computational domain and boundary conditions. Boundary condition (BC) represents the effect surrounding the model or domain. BC could dictate the solution inside of the domain and have significant effects on the accuracy of the solution. Generally, BC consists of the velocity inlet, wall, and pressure outlet, as presented in Fig. 2. As a good practice, a preliminary CFD simulation of an empty computational domain that accurately represents the flow field should be performed by incorporating the measured flow data at the inlet boundary through numerical modeling (Blocken et al., 2007).

Fig. 2. Computational domain with building models for CFD simulation (Blocken et al., 2007).

The wind field profile reproduced in the wind tunnel corresponded to the Architectural Institute of Japan (AIJ) standards (AIJ, 1996). ( ) = 1.7( ) ∝ , < ≤ , (1) ( ) = 1.7( ) ∝ , ≤ , (2) where α is the exponent, Z G is a reference height of the atmospheric boundary layer (ABL), Z b represents the characteristic dimension of the surface roughness element, and U ref is the reference wind velocity measured at a height from the wind tunnel floor. The turbulent intensity is another important parameter and can be described as below: ( ∝ ) 2.45√ ( ) ∝ (3) Where U is the mean wind velocity ( m/s ), H is the height above sea level ( m ), Hg represents a reference height ( m ), and is the power-law exponent describing the height dependence, and k is the surface drag coefficient. At the selection of the numerical method, there are several types of turbulent models, e.g, Large Eddy Simulation (LES), and Reynolds Averaged Navier Stokes (RANS). The use of LES to simulate unsteady grid-scale eddies using