| Popis: |
Both modal and non-modal stability analysis of a channel flow laden with light particles is presented. The particles are assumed spherical and solid and their presence modeled using two-way coupling, with Stokes drag, added mass and fluid acceleration as coupling terms. The Stokes drag is a function of particle relaxation time and mass fraction, while added mass and fluid acceleration are a function of mass fraction and density ratio. When the particles considered have a density ratio of order one, all three terms are important. Modal analysis shows a decrease in critical Reynolds number proportional to the mass fraction for all particle relaxation times at a density ratio of one. Lighter particles decrease the critical Reynolds number further, whereas heavier particles might increase the critical Reynolds number. Most effect is found when the stability Stokes number is of order one. Non-modal analysis shows that the transient growth of the total system is enhanced in proportion to the particle mass fraction, as observed in flows laden with heavy particles. The generation of streamwise streaks is still the most dominant disturbance-growth mechanism in particle laden flows with light particles. Thus, the presence of particles may not work to delay the transition. QS 20120316 |
