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Three-Dimensional Large Eddy Simulation of Continuous Density Currents

Najafpour, Nategheh | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44386 (08)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Firoozabadi, Bahar; Afshin, Hossein
  7. Abstract:
  8. When a fluid moves inside another fluid while they have unequal density, a phenomena occurs which is called density (or gravity) current. Therefore density difference and gravity are key factors of density current generation. Due to application in engineering and geology, it is essential to investigate and analyze the above mentioned phenomena. Dam reservoirs, sandstorm in deserts, snow slide onset and falling, ash clouds produced during eruption of a volcano, and spreading of density current due to the collapsing of reservoirs are some examples of gravity current. There are lots of methods to simulate the turbulence of density current like DNS or RANS. But DNS has high computational cost and also RANS suffers from insufficient accuracy for simulation of density current. Considering the importance of density current behavior analysis which was discussed above, in the present study, simulation and numerical investigation of density current is done using the Large Eddy Simulation (LES) method. Domain of study contains an obstacle with different heights which current passing on. Variation of straky lines, contours of constant concentration, contours of vorticity, vertical structures, stream lines, variation of bed shear stress, and drag force variation with time on the obstacle are principal results of this study. The results show that obstacle height affects velocity and concentration distribution of the current. Increasing of obstacle height decreases the average velocity of fluid and increases height of density current. On the other hand, obstacle height increment, promotes the reverse flow and it increases the velocity of reverse flow
  9. Keywords:
  10. Obstruction ; Richardson Number ; Density Current ; Large Eddy Simulation (LES) ; Turbulent Model

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