Hamid Bazgirkhoob Dissertation Defense
“Bed Pressure and Velocity Distributions in a Box Culvert Downstream of a Sluice Gate”
3:00 pm –
5:00 pm
Scott Engineering Center Link
Room: N105
Additional Info: SLNK
April 10
3:00 PM
Scott Engineering Center Link N105
Advisor: David Admiraal
Turbulence distributions and pressure fluctuations downstream of a sluice gate in a culvert flow with a fully submerged hydraulic jump are investigated for different Reynolds numbers based on gate height. Pressure transducers were used to monitor pressures and pressure fluctuations on the bed. Particle Image Velocimetry (PIV) was used to capture turbulence distributions through the culvert. Results show that minimum average pressures occur very close to the gate at the location of maximum x-velocity. During the test period, extreme pressure fluctuations in positive and negative domains are observed. The Probability Density Functions (PDF) of the peak pressures are non-Gaussian and require extreme-value distribution analysis. The selected experiment time interval of 20 minutes was capable to validate approximately 1000T (Integral Time Scale) of the maximum time scales. The probability Density Functions of the pressure distributions follow Gumbel Type I Distribution with negative skewness dominant for minimum pressure distributions and positive skewness for maximum pressure distributions. The PDF of the minimum and maximum pressure fluctuations have low values for minimum and high values for maximum at the beginning of the flume. Downward the flume, the distributions move closer to each other.
To model turbulence stresses, Reynolds-Averaged Navier-Stokes (RANS) turbulence models are employed. Parallel, pressure-based, steady-state commercial code ANSYS FluentTM was employed as the RANS solver. Volume of fluid (VOF) method is used to calculate the free surface in the forebay and tail tank. Reynolds Stress turbulence closure Model (RSM) and Realizable k-? (RKE) turbulence models simulate the submerged hydraulic recirculation zone and the tail water free surface well, as validated with PIV experimental results. It is concluded that RSM is more capable to simulate turbulence characteristics for a 3-D model due to dynamic equations for the Reynolds stress tensor.
3:00 PM
Scott Engineering Center Link N105
Advisor: David Admiraal
Turbulence distributions and pressure fluctuations downstream of a sluice gate in a culvert flow with a fully submerged hydraulic jump are investigated for different Reynolds numbers based on gate height. Pressure transducers were used to monitor pressures and pressure fluctuations on the bed. Particle Image Velocimetry (PIV) was used to capture turbulence distributions through the culvert. Results show that minimum average pressures occur very close to the gate at the location of maximum x-velocity. During the test period, extreme pressure fluctuations in positive and negative domains are observed. The Probability Density Functions (PDF) of the peak pressures are non-Gaussian and require extreme-value distribution analysis. The selected experiment time interval of 20 minutes was capable to validate approximately 1000T (Integral Time Scale) of the maximum time scales. The probability Density Functions of the pressure distributions follow Gumbel Type I Distribution with negative skewness dominant for minimum pressure distributions and positive skewness for maximum pressure distributions. The PDF of the minimum and maximum pressure fluctuations have low values for minimum and high values for maximum at the beginning of the flume. Downward the flume, the distributions move closer to each other.
To model turbulence stresses, Reynolds-Averaged Navier-Stokes (RANS) turbulence models are employed. Parallel, pressure-based, steady-state commercial code ANSYS FluentTM was employed as the RANS solver. Volume of fluid (VOF) method is used to calculate the free surface in the forebay and tail tank. Reynolds Stress turbulence closure Model (RSM) and Realizable k-? (RKE) turbulence models simulate the submerged hydraulic recirculation zone and the tail water free surface well, as validated with PIV experimental results. It is concluded that RSM is more capable to simulate turbulence characteristics for a 3-D model due to dynamic equations for the Reynolds stress tensor.
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