The Propulsive Performance of Side-By-Side Foils at a Range of Re and St

The hydrodynamic interactions between two foils placed in side-by-side arrangement are investigated using Direct Numerical Simulation at Reynolds numbers of 1000, 2000 and 4000, and Strouhal numbers (St) ranging from 0.25 to 0.5. The transverse spacing and phase difference between the foils are kept constant. Dynamic motions of the foils are simulated using dynamic mesh morphing technique in OpenFOAM. Coefficients of thrust and power, as well as efficiency, are used to compare the performance of foils. The interactions between foils are also studied through varying the St of individual foils. The performance parameters of the system are observed to depend on both St and Re. In the range of St, the combined efficiency of the system reaches the maximum at St =0.4. The system experiences a thrust enhancement with increasing Re although the coefficient of power remains stable in the Re range. The results are used to evaluate the applicability of the scaling law developed by Floryan et al. (2017) on an isolated foil. The scaling laws for tandem foils in side-by-side arrangements are also developed.