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Santanu Ghosh
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Santanu Ghosh
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Santanu Ghosh
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Ghoshy, Santanu
Ghosh, S.
Ghosh, Santanu
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13 results
Now showing 1 - 10 of 13
- PublicationDynamical Systems Analysis of a Zero-Equation Transition Model(01-10-2021)
;Sandhu, Jatinder Pal Singh - PublicationNumerical simulation of effects of mesoflaps in controlling shock/boundary-layer interactions(01-01-2012)
; ;Edwards, Jack R.Choi, Jung IlThis work uses an immersed-boundary method to simulate the effects of an array of aeroelastic mesoflaps in controlling oblique shock/turbulent boundary-layer interactions. A loosely coupled approach is adopted for the fluid-structure interaction problem, with separate solvers used for the fluid and the structure. The mesoflaps are rendered as immersed objects for the fluid solver and modeled as cantilevered Euler-Bernoulli beams for the structural solver. Simulations are performed for a Mach 2.46 shock/boundary-layer interaction with and without control, based on experiments conducted at University of Illinois at Urbana-Champaign. Both Reynolds-averaged Navier-Stokes and hybrid large-eddy/Reynolds-averaged Navier-Stokes turbulence closures are used. Comparisons made with experimental laser Doppler anemometry data and wall pressure measurements for flows with and without control show reasonable agreement, with better predictions away from the separation region. An analysis of the flow indicates that the mesoflap control system does not eliminate axial flow separation. Also, analysis of the frequency content of the mesoflap deflections suggests that a correlation might exist between the dominant frequency of the Euler-Bernoulli flap deflection and the low-frequency shock motion observed in separated flows. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. - PublicationPositioning of normal shock in a novel constant-area test section: A numerical study(01-01-2019)
;Roy, Shobhan ;Subramaniam, Karthik - PublicationA local correlation-based zero-equation transition model(15-01-2021)
;Sandhu, Jatinder Pal SinghIn this work, the local correlation-based one-equation transition model (Menter, F.R., Smirnov, P.E., Liu, T. and Avancha, R., A one-equation local correlation-based transition model. Flow, Turbulence and Combustion, vol. 95, no. 4, pp. 583–619, 2015.) is transformed into a zero-equation transition model. The new model provides an attractive choice in terms of quick implementation of a transition model in existing turbulent flow solvers with Menter's shear-stress transport (SST) turbulence model, as it only introduces three extra source terms in the transport equation of turbulent kinetic energy. The model is validated against a set of benchmark flat-plate test cases: T3 series and SK, and also subsonic flows past two different airfoils: Aerospatiale A-airfoil (Re=2.1million) and E387 (Re=0.2million), and finally applied to a transonic flow over 3D DLR-F5 wing (Re=1.5million). Results show that the proposed model produces similar transition prediction as the one-equation transition model, with a reduced computational effort. The computations are performed with an in-house finite-volume solver for compressible turbulent flows on block-structured grids. - PublicationFlow control in Mach 4.0 inlet by slotted wedge-shaped vortex generators(01-01-2017)
;Varma, DeepakThis work makes an attempt to determine an effective streamwise and spanwise arrangement of a relatively novel control device, the sub-boundary-layer slotted vortex generator, having a slot radius of 60% of device height, to minimize the flow separation in a realistic mixed-compression inlet geometry. The inlet considered for the simulations is based on the experiments conducted by S. Emami et al. at NASA Langley Research Center at Mach 4.03 to determine performance of an inlet/isolator configuration. The present work uses a computational domain based on one such inlet configuration, having the smallest-sized cowl and a large convergence angle, to produce a strong cowl-lip shock. Results indicate that the extent of flowseparation gets successively reduced, as the device trailing edge ismoved closer to the interaction region. It is also observed that the inlet width determines the optimal spacing of the device, and that in presence of sidewall boundary layers, the device performs better when positioned closer to the inlet center plane than the sidewall. The computations in thiswork are performed using the REACTMB code, suitable for high-speed turbulent flows. The turbulence model used is Menter's shear stress transport model. - PublicationNovel vortex generator for mitigation of shock-induced flow separation(01-01-2016)
;Sharma, Pushpender ;Varma, DeepakA novel vortex generator, termed as "slotted vortex generator," is proposed in this study. Computations are conducted for supersonic flow at a freestream Mach number of 2.5 past single vortex generators of three different heights. For each device height h, three values of the slot radius r = 0.3h, 0.4h, and 0.6h are used. Comparisons made with a standard wedge-type vortex generator using streamwise-velocity profiles, near-surface streamwise-velocity contours, pitot pressure deficit contours, etc., indicate that the new device has less device drag and produces fuller near-surface streamwise velocities downstream of the device. It is observed that the primary counter-rotating vortex pair formed due to the vortex generator lifts off at a slower rate when a slotted vortex generator is used. Computations of an impinging oblique-shock/boundary-layer interaction at Mach 2.5 for a flow turning angle of 7 deg, with flow control using (separately) an array of slotted and standard vortex generators, indicate that the slotted vortex generators with r/h =0.6 are most effective in reducing the region with reversed flow when placed closer to the shock/boundary-layer interaction region. - PublicationAerodynamic study of single corrugated variable-camber morphing aerofoil concept(01-01-2021)
;Dhileep, K.; ;Gautham Vigneswar, P. N. ;Soni, P.; ; Arockiarajan, A.Camber morphing is an effective way to control the lift generated by any aerofoil and potentially improve the range (as measured by the lift-to-drag ratio) and endurance (as measured by Cl3/2/Cd). This can be especially useful for fixed-wing Unmanned Aerial Vehicles (UAVs) undergoing different flying manoeuvres and flight phases. This work investigates the aerodynamic characteristics of the NACA0012 aerofoil morphed using a Single Corrugated Variable-Camber (SCVC) morphing approach. Structural analysis and morphed shapes are obtained based on small-deformation beam theory using chain calculations and validated using finite-element software. The aerofoil is then reconstructed from the camber line using a Radial Basis Function (RBF)-based interpolation method (J.H.S. Fincham and M.I. Friswell, "Aerodynamic optimisation of a camber morphing aerofoil,"Aerosp. Sci. Technol., 2015). The aerodynamic analysis is done by employing two different finite-volume solvers (OpenFOAM and ANSYS-Fluent) and a panel method code (XFoil). Results reveal that the aerodynamic coefficients predicted by the two finite-volume solvers using a fully turbulent flow assumption are similar but differ from those predicted by XFoil. The aerodynamic efficiency and endurance factor of morphed aerofoils indicate that morphing is beneficial at moderate to high lift requirements. Further, the optimal morphing angle increases with an increase in the required lift. Finally, it is observed for a fixed angle-of-attack that an optimum morphing angle exists for which the aerodynamic efficiency becomes maximum. - PublicationNumerical investigation of lift enhancement in flapping hover flight(01-05-2020)
;Bharadwaj, Anand SundaresanThe focus of this work is the study of lift enhancement in flapping hover flight using numerical simulations. An idealized set of kinematics for a NACA0012 airfoil consisting of sequential translations and rotations is considered for this purpose, such that the Cl response can be demarcated into translational and rotational parts, which facilitates comparison of forces attributed to translation and rotation. Additionally, comparisons with pure translation and pure rotation are done to isolate the effect of wing-wake interactions. The investigation reveals that the majority of lift is produced in the translational phase. The wing-wake interactions affect the translational phase of the response more than the rotational phase. However, the rotation rate determines the extent of influence of wing-wake interactions on the translational lift response. The effect of different durations of overlap between the translational and rotational motions is also assessed based on the Cl time histories and mean Cl, and the study reveals that an optimum duration of overlap can maximize the lift. An immersed-boundary method with integrated surface-load reconstruction capabilities is used for the computations presented here. The reconstruction of the surface stresses and their integration are carried out with the framework of a parallel solver. The method is validated for a flow past a NACA0012 airfoil executing a non-periodic plunge motion and a non-periodic pitch/plunge motion and a flow around an elliptic airfoil executing a flapping motion. - PublicationEvaluation of ramp-type micro vortex generators using swirl center tracking(01-01-2018)
;Singh Sandhu, Jatinder Pal; ;Subramanian, ShashankSharma, PushpenderThe evolution of the primary vortex pair downstream of micro vortex generators placed in a supersonic stream is compared using a swirl center tracking technique, for standard, slotted, and split-ramp-type vortex generators. Evolution of vortex strength, determined using circulation, and distribution of vortices, determined using contours of helicity, are also compared. Results show that secondary vortices emerge stronger, and liftoff heights drop, with the introduction of slot (slotted micro vortex generator) or gaps (split-ramp micro vortex generator). Near-surface contours of axial velocity and integral properties of the boundary layer are then compared to evaluate the effects of the evolution of the vortical structures on the flowfield. Results shows that the split-ramp device results in the most energetic near-surface flow but the worst outgoing boundary-layer integral properties, whereas the slotted-ramp devices with taper fare well on both counts. The computations performed in this work involve supersonic flow past single micro vortex generators at Mach 2.5 and use an immersed-boundary method to render the control devices. The flow solver is suitable for high-speed turbulent flows and has been extensively validated in earlier works. The turbulence model used is Menter's k − ω∕k − ε shear-stress transport version. - PublicationA face-based immersed boundary method for compressible flows using a uniform interpolation stencil(20-10-2022)
;Kasturi Rangan, M. L.N.V.In this study, an immersed boundary method developed for compressible viscous flows (Ramakrishnan, R., Girdhar, A., & Ghosh, S. (2016). Immersed Boundary Methods for Compressible Laminar Flows) is modified to improve their stability and robustness. The embedded object is represented as a set of line segments in two dimensions with their outward unit normal vectors specified. A forcing method that leverages the finite volume approach is used, wherein the solution at the cell interfaces that lie near the boundaries of the embedded solid is reconstructed to implicitly satisfy boundary conditions at the immersed surface. The proposed immersed boundary method is validated for transonic inviscid flow past a bump in a channel, supersonic flow past a circular cylinder, transonic viscous flow past a NACA0012 airfoil, and supersonic viscous flow past a circular cylinder. The results are compared with simulations from the literature using contours of flow properties, surface pressure, or Mach number plots and show good agreement.