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Full-Text Articles in Engineering
Sensitivity Analysis Of Frost Deposition In Turbulent Flow Over A Cold Plate Using Direct Numerical Simulation, N. Farzaneh, Nadim Zgheib, S. A. Sherif, S. Balachandar
Sensitivity Analysis Of Frost Deposition In Turbulent Flow Over A Cold Plate Using Direct Numerical Simulation, N. Farzaneh, Nadim Zgheib, S. A. Sherif, S. Balachandar
Mechanical Engineering Faculty Publications and Presentations
We use a recently-developed, turbulence-informed physics-based model to study frost buildup over a flat plate subjected to turbulent flow. The plate temperature is held fixed but varied across simulations in the range −10◦C ≤ T∗ p ≤ −5◦C. Similarly, the free-stream temperature and humidity ratio are also held fixed but varied across simulations in the range 0◦C ≤ T∗∞ ≤ 20◦C and 3.77 × 10−3 ≤ ew∞ ≤ 1.47×10−2, respectively. We find the Nusselt and Sherwood numbers, when scaled by the frost surface to free stream temperature and humidity ratio difference, respectively, to become independent of free-stream temperature and humidity …
A Physics-Based Model For Frost Buildup Under Turbulent Flow Using Direct Numerical Simulations, Nadim Zgheib, N. Farzaneh, S. Balachandar, S. A. Sherif
A Physics-Based Model For Frost Buildup Under Turbulent Flow Using Direct Numerical Simulations, Nadim Zgheib, N. Farzaneh, S. Balachandar, S. A. Sherif
Mechanical Engineering Faculty Publications and Presentations
We present a new model for frost buildup under turbulent (and laminar) flow using direct numerical simulations. The physical model consists of two layers, the air and the frost. The air layer is fully resolved and consists of solving for the velocity, temperature, and vapor mass fraction fields. The frost layer thickness is resolved using conservation of mass and energy. Both phases are dynamically coupled using the immersed boundary method. Three-dimensional simulations are conducted in an open-channel configuration. A number of challenges need to be overcome to make these simulations feasible. First, to enforce far-field conditions of zero …
Force And Torque Model Sensitivity And Coarse Graining For Bedload-Dominated Sediment Transport, Liheng Guan, Jorge Salinas, Nadim Zgheib, S. Balachandar
Force And Torque Model Sensitivity And Coarse Graining For Bedload-Dominated Sediment Transport, Liheng Guan, Jorge Salinas, Nadim Zgheib, S. Balachandar
Mechanical Engineering Faculty Publications and Presentations
We present results from Euler–Lagrange simulations of turbulent flow over an erodible monodisperse bed of particles at a shear Reynolds number of R e τ = 180 . The Galileo number G a and the ratio of Shields to the critical Shields number Θ / θ c r were varied in the range 11.4 to 29.8 and 1.32 to 5.98, respectively. Two drag force models were investigated along with the influence of lift, particle rotation, and tangential collision forces for each model. Both models give similar results as far as mean particle flux and Shields stress are concerned, however we …
On The Role Of Sidewalls In The Transition From Straight To Sinuous Bedforms, Nadim Zgheib, S. Balachandar
On The Role Of Sidewalls In The Transition From Straight To Sinuous Bedforms, Nadim Zgheib, S. Balachandar
Mechanical Engineering Faculty Publications and Presentations
We present results from direct numerical simulation on the transition from straight-crested to sinuous-crested bedforms. The numerical setup is representative of turbulent open channel flow over an erodible sediment bed at a shear Reynolds number of Reτ = 180. The immersed boundary method accounts for the presence of the bed. The simulations are two-way coupled such that the turbulent flow can erode and modify the bed, and in turn, the bed modifies the overlying flow. Coupling from the flow to the bed occurs through the Exner equation, while back coupling from the bed to the flow is achieved by …