Numerical Investigations of Transient Wind Shear from Passing Vehicles near a Road Structure California State Univ-Long Beach

Format:

Book

Conference/Event

Author/Creator:

Rahai, Hamid, author.

Contributor:

Begum, Assma

Conference Name:

SAE WCX Digital Summit (2021-04-13 : Live Online, Pennsylvania, United States)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2021

Summary:

Unsteady numerical simulations of a moving Ahmed body under a freeway overpass at different distances from the bridge columns have been performed for evaluating transient wind shear and wind load on and near these columns. The Ahmed body had dimensions of 1.62 m height (H), 5 m length (L), and 1.86 m width (W) with a hatchback rear at 35 degrees slope angle from the top, starting at 4.14 m from the vehicle's front. These dimensions are comparable to a small passenger's Van/SUV. The vehicle was spaced at 0.28 m above the road. The control volume for the computational domain that encompasses the bridge has dimensions of X=30 m, Y= 11.25m, and Z= 14.5m with a grid size of 0.0375m. Here X is the direction of the vehicle, Y is the perpendicular distance and Z is the spanwise direction (across the road). The overpass bridge had a height of about 6.2 m. The blockage ratio, the ratio of the projected area of the Ahmed body to the projected area of the bridge underpass was less than 3%. The freestream mean velocity in the axial direction was 23 m/sec. which corresponds to a Reynolds number based on an equivalent diameter based on the project vehicle area of 2.9x106. Simulations were performed for the moving vehicle having distances of 0.75W, 1W, and 2W away from the column rows. Here W is the width of the vehicle.Results indicate as the vehicle gets closer to the columns, a region of high pressure is formed upstream of the vehicle and the columns. The shorter the distance, the higher the pressure force. The maximum force experienced is approximately 200 pascals (pa).Flow separation in the wake creates oscillatory flow, ejecting high momentum fluids downstream. Significant oscillatory flow is seen at 1W-2W downstream, beyond which the wake expands and dissipates. At 6W downstream, the wake width has expanded to approximately 6W. As the vehicle gets closer to the columns, high momentum oscillatory flow impinges on the columns. It is interesting to note that significant expansion of the wake is seen downstream, beyond the first column for Z=0.75W and 1W which indicates a potential source for capturing wind energy at this location

Notes:

Vendor supplied data

Publisher Number:

2021-01-0964

Access Restriction:

Restricted for use by site license