Numerical Simulation of Buoyant Pulsating Exchange Flow through Circular Opening in Horizontal Partition

Authors

  • B. Gera Reactor Safety Division, Bhabha Atomic Research Centre Trombay, Mumbai, India- 400085
  • P. K. Sharma Reactor Safety Division, Bhabha Atomic Research Centre Trombay, Mumbai, India- 400085
  • R. K. Singh Reactor Safety Division, Bhabha Atomic Research Centre Trombay, Mumbai, India- 400085
  • K. K. Vaze Reactor Safety Division, Bhabha Atomic Research Centre Trombay, Mumbai, India- 400085

Keywords:

salt water, horizontal partition, CFD, oscillation, circular opening

Abstract

An interesting transport phenomenon is observed through openings between two compartments separated by a thin, vented, horizontal partition such as those between containment internals in nuclear power systems, in industrial installations in event of fire, passive cooling of heated structures and in natural building ventilation. A heavier fluid located on the top of a lighter fluid and separated by a horizontal vent constitutes a gravitationally unstable system. Horizontal vents produce flow, which are unstable with irregular oscillatory behavior. The objective of the present work was to simulate such type of flow across a circular opening in horizontal partition in presence of buoyancy force. Unsteady, axisymmetric Navier-Stokes equations have been solved with Finite Volume Method. The equations were solved using the in-house CFD code based upon the well-established pressure-based finite volume methodology. In terms of temporal differencing second order accurate Crank-Nicolson scheme was used. Interpolation to cell faces for the convective terms was performed using a third order QUICK scheme, second order central differencing was used for the viscous terms. Pressure-velocity coupling was based on the SIMPLE procedure. The upper chamber was filled with salt water and the lower chamber with fresh water, creating a density differential between the two chambers. Opposing forces at the interface created a gravitationally unstable system, and an oscillating exchange of fluid developed. Three different cases for vent length to diameter ratio (L/D) 0.008, 0.0376 and 0.106 from a reported experiment were examined. The pulsation frequencies and their decay with time have been determined. The flow coefficients were computed and compared with experimental results.

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Published

2021-01-18

How to Cite

Gera, B. ., Sharma, P. K. ., Singh, R. K. ., & Vaze , K. K. . (2021). Numerical Simulation of Buoyant Pulsating Exchange Flow through Circular Opening in Horizontal Partition . CFD Letters, 4(1), 20–32. Retrieved from https://akademiabaru.com/submit/index.php/cfdl/article/view/3345

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