U Ghia

Bio: U Ghia is an academic researcher from University of Cincinnati. The author has contributed to research in topics: Venturi effect & Mechanics. The author has an hindex of 1, co-authored 1 publications receiving 3728 citations.

Special Issue on Fluids Engineering Research in Honor of the Life and Achievements of Professor Kirti Ghia - A Pioneer in Computational Fluid Dynamics

Abstract: Understanding particle detachment from surfaces is necessary to better characterize dust generation and entrainment. Previous work has studied the detachment of particles from flat surfaces. The present work generalizes this to investigate the aerodynamics of a particle attached to various locations on a model hill. The present work serves as a model for dust aerosolization in a tube, as powder is injected into the Venturi Dustiness Tester. The particle is represented as a sphere in a parallel plate channel, or, in two dimensions, a cylinder oriented perpendicular to the flow. The substrate is modified to include a conical hill (3d) or wedge (2d), and the test particle is located at various positions on this hill. The governing incompressible Navier-Stokes equations are solved using the finite-volume FLUENT code. The coefficients of lift and drag are compared with the results on the flat substrate. Enhanced drag and significantly enhanced lift are observed as the test particle is situated near the summit of the hill.

Numerical Investigation of Aerosolization in the Venturi Dustiness Tester: Aerodynamics of a Particle on a Hill.

Abstract: Understanding particle detachment from surfaces is necessary to better characterize dust generation and entrainment. Previous work has studied the detachment of particles from flat surfaces. The present work generalizes this to investigate the aerodynamics of a particle attached to various locations on a model hill. The present work serves as a model for dust aerosolization in a tube, as powder is injected into the Venturi Dustiness Tester. The particle is represented as a sphere in a parallel plate channel, or, in two dimensions, as a cylinder oriented perpendicular to the flow. The substrate is modified to include a conical hill (3D) or wedge (2D), and the test particle is located at various positions on this hill. The governing incompressible Navier-Stokes equations are solved using the finite-volume FLUENT code. The coefficients of lift and drag are compared with the results on the flat substrate. Enhanced drag and significantly enhanced lift are observed as the test particle is situated near the summit of the hill.

Comparison of the V&V10.1 and V&V20 Modeling Error Quantification Procedures for the V&V10.1 Example

Abstract: The determination of the transverse tip deflection of an elastic, hollow, tapered, cantilever, box beam under a uniform loading applied over half the length of the beam presented in the V&V10.1 standard is used to compare the application of the validation procedures presented in the V&V10.1 and V&V20 standards. Both procedures aim to estimate the modeling error of the mathematical/computational model used in the simulations taking into account the variability of the modulus of elasticity of the material used in the beam and the rotational flexibility at the clamped end of the beam. The paper discusses the four steps of the two error quantification procedures: 1- characterization of the problem including all the assumptions and approximations made to obtain the experimental and simulation data; 2-selection of the validation variable; 3- determination of the different quantities required by the validation metrics in the two error quantification procedures; 4- outcome of the two validation procedures and its discussion. The paper also discusses the inclusion of experimental, input and numerical uncertainties (assumed or demonstrated to be negligible in V&V10.1) in the two validation approaches. This simple exercise shows that different choices are made in the two alternative approaches, which lead to different ways of characterizing the modeling error. The topics of accuracy requirements and validation comparisons (model acceptance/rejection) for engineering applications are not addressed in this paper.