Numerical analysis of flow past over a triangular rod through passive control method

A two-dimensional numerical study is conducted to investigate the effect of a control plate length on flow past over a triangular rod through a lattice Boltzmann method. The Reynolds number (V-max d/nu) is taken within the range from Re = 50-200, and the length (L) of the control plate is varied from L = 1-5. First, we checked the adequacy of a grid point by selecting different values of grids and studied the effect of a computational domain at different values of upstream (L-u), downstream (L-d) distances and changing the height (H) of the channel. After that, we studied the effect of fluid forces on flow past a single triangular rod and then by attaching the control plate by varying its length. The results are obtained in terms of vorticity contour, drag (C-D) and lift (C-L) coefficients, and calculation of physical parameters (CDmean, CDrms, CLrms, and St). In terms of vorticity contour, we examined four various types of flow regimes. These are (i) steady flow regime (SFR), (ii) quasi-steady flow regime (QSFR), (iii) shear layer reattachment flow regime, and (iv) single bluff body flow regime based on the flow structure mechanism. In calculation of physical parameters, we observed that the mean drag coefficient contains a maximum value for the case of the single triangular rod as compared to presence of the attached control plate. Second, it is noticed that, as the Reynolds number increases, the values of CDmean gradually decreases, but at the highest range of Reynolds number and largest length of the control plate, the value of the mean drag coefficient increases and produces more fluid forces. CDrms also shows similar behavior like CDmean. The root mean square values of lift coefficients become zero at (L, Re) = (1, 50), (2, 50), (2, 80), (3, 50), (3, 80), (3, 100), (4, 50), (4, 80), (4, 100), (4, 120), (5, 50), (5, 80), (5, 100), (5, 120), and (5, 150), respectively. The St containing maximum value at (L, Re) = (2, 200) and minimum value at (L, Re) = (5, 200). Furthermore, at lengths L = 1-5, the value of St = 0 due to no lift forces at (L, Re) = (1, 50), (2, 50), (3, 50), and (4, 50) and (2, 80), (3, 80), (3, 100), (4, 120), and (5, 150), respectively. The maximum reduction in CDmean is found to be about 16.89%. Overall, the findings suggest complex interactions between Reynolds number, control plate length, and various coefficients, impacting the flow structure and shedding characteristics.