Abstract
A numerical simulation by a three-dimensional vortex blob method has shown that an axisymmetric sinusoidal forcing generates a vortex ring with circulation which is greater than that for the unforced flow, under the condition that the same volume of fluid issues from a circular nozzle during a fixed time interval. The time interval is chosen as 4.0(2R/U) based on the experiment of Gharib et al. (1998), where li is the radius of the nozzle and U is the average velocity of the issuing fluid. At a fixed amplitude of forcing, this maximum circulation is realized at a forcing frequency of 0.125( U/2H). This is because most of the circulation shed from the nozzle is absorbed into the vortex ring at this optimum frequency. The maximum circulation is greater than that of the unforced flow by an amount proportional to the amplitudes squared. This is discussed in terms of the circulation shed from the nozzle during the issuing time.
| Original language | English |
|---|---|
| Pages (from-to) | 3986-3992 |
| Number of pages | 7 |
| Journal | Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B |
| Volume | 65 |
| Issue number | 640 |
| DOIs | |
| Publication status | Published - 1999 Dec |
Keywords
- Axisymmetric sinusoidal forcing
- Maximum circulation
- Numerical analysis
- Vortex blod method
- Vortex ring
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanical Engineering