2 research outputs found
Instabilities of Decelerating Flow
This paper numerically investigates the instability characteristics of
decelerating flows. The flow dynamics and temporal evolution of coherent
structures in a diverging section with mild spatial pressure gradient are
analyzed using numerical experiments with Incompact3d code. The unsteady nature
of flow and adverse pressure gradient is the reason for inflectional velocity
profiles, results into boundary layer separation and instability with reverse
flow and later on it leads to vortex formation. Vortex formation time is found
by vortex Reynold's number. Time of first vortex formation, non-dimensional
vortex formation times with Reynold's number etc. are validated with an
experimental results.Comment: Proceedings of the 25th National and 3rd International ISHMT-ASTFE
Heat and Mass Transfer Conference (IHMTC-2019
Assessment of Pressure Based Solver in Resolving Complex Shock Wave Phenomenon
This study presents a critical assessment of a pressure-based solver (PBS) in
resolving complex interactions of shocks, turbulent structures etc.. The
canonical problem chosen to be resolved in this study is of mode staging in
axisymmetric supersonic jet screech. The screech phenomenon exhibits staging
behavior characterized by frequency and azimuthal structure changes at specific
frequencies. The PBS simulations in the popular ANSYS Fluent software-suite
were validated against numerical work and experimental measurements, and
results were analyzed. Simulations are performed on supersonic jets which emits
dual high frequency screech tones at particular Mach numbers. At lower end of
these supersonic Mach numbers, the flow can involve vanishingly weak shock
strengths which is routinely captured in experiments and by density based
solvers in literature. The limitations of the pressure-based solver in
resolving complex shock flow phenomena and predicting mode staging are
highlighted at vanishingly weak Mach numbers, emphasizing the need for further
investigation given the recent popularity of such solvers for all Mach numbers
including in high-speed flow.Comment: 14th Asian Computational Fluid Dynamics Conference, 30th October -
02nd November, 2023, Bengalur