Q2. What is the consequence of evaluating the circulation with max instead of 515?
A consequence of evaluating the circulation with max instead of 5−15 is that the circulation curve would raise above 0 during the vortex diffusion phase.
Q3. What was the primary method of vortex dissipation without the addition of obstacles?
As the primary method of vortex dissipation without the addition of obstacles was from the interaction between vortex sheet and ground boundary flow, the usage of vortex generator type obstacle could increase the contact time between the two and ultimately increase the energy dissipated from the wake vortex.
Q4. What was the numerical solver used for the current obstacle shape study?
The numerical solver employed a hybrid Pressure Implicit with Splitting of Operator (PISO) and Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm.
Q5. What is the reason for the decay of a counter rotating vortex pair?
Previous studies on vortex instability in ground effect have shown that while it is possible for Crow instability to develop at very low Reynolds number and large initial height (h0 > 10b0), the decay of a counter rotating vortex pair is largely due to the instability from the vortex–ground interaction [1,6,19,20].
Q6. How many meshes were attached to the baseline?
and 0.0003 m. A fourth, more refined wall mesh, was attached to the baseline mesh after initial simulations, as it became apparent that the y1 size from the baseline mesh was insufficiently refined to obtain good agreement to experimental data.
Q7. What was the boundary layer mesh used in the DLR study?
boundary layer mesh was attached to all sides of the obstacle in the current study, whereas it was only applied to the floor patch in the DLR study.
Q8. What is the general effect of the velocity of circulating flow about the vortex core?
In general, the velocity of circulating flow about the vortex core was weakerfurther away from the vortex core, and would generate weaker SVS that no longer significantly affects the wake vortex.
Q9. Why was the boundary condition used to prevent disturbance to the vortex structure?
The compromise of using periodic boundary condition was made in order to ensure that disturbance to the vortex structure did not appear along the end wall due to momentum lost whensubjected to pressure outlet boundary condition.
Q10. How many plates were placed at a certain interval?
The cross-sectional profile of the obstacles were reduced to 0.1b0 × 0.2b0 in height and width; the plates were placed at 0.45b0 interval.
Q11. What is the effect of the modeled boundary layer flow on the mesh?
The additional flow energy removed due to the lack of resolved or modeled boundary layer flow would con-tribute to the circulation reduction for the coarser mesh as shown in Fig.
Q12. What was the circulation plot for the baseline obstacle?
The circulation plot from Fig. 10 showed that only employing a single pair of baffle type obstacle was less effective at x∗ = 0 and x∗ = 3.6 comparing to the simulation result with the square cylinder obstacle.
Q13. How did the flow visualization for = 79 be performed?
In order to gain more insight on the flow interaction that led to the different circulation curves observed, flow visualization with iso-surface plot for ‖ω∗‖ = 79 was performed.
Q14. How was the effect of the obstacle shape on the wake dissipation rate evaluated?
The influence of different obstacle shapes on the wake dissipation rate was evaluated by calculating the vortex circulation on sampling planes located at x∗ = 0, x∗ = 1.05, and x∗ = 3.6.
Q15. Why was the initial rebound height higher in the LES and WSG data?
The difference in initial rebound height between the present LES and WSG data could be due to the lack of background perturbations, which reduced the current simulations to a quasi-2D state.