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S K Bhattacharyya

Bio: S K Bhattacharyya is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Turbulence & Reynolds-averaged Navier–Stokes equations. The author has an hindex of 2, co-authored 2 publications receiving 21 citations.

Papers
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TL;DR: In this paper, the effect of angle of attack over flow structure, force coefficients and wall related flow variables are discussed in detail, and the non-linear k-e turbulence model is validated against DARPA Suboff axisymmetric hull.
Abstract: This paper addresses the Computational Fluid Dynamics Approach (CFD) to simulate the flow over underwater axisymmetric bodies at higher angle of attacks. Three Dimensional (3D) flow simulation is carried out over MAYA Autonomous Underwater Vehicle (AUV) at a Reynolds number (Re) of 2.09×10 6 . These 3D flows are complex due to cross flow interaction with hull which produces nonlinearity in the flow. Cross flow interaction between pressure side and suction side is studied in the presence of angle of attack. For the present study standard k-e model, non-linear k-e model models of turbulence are used for solving the Reynolds Averaged Navier-Stokes Equation (RANS). The non-linear k-e turbulence model is validated against DARPA Suboff axisymmetric hull and its applicability for flow simulation over underwater axisymmetric hull is examined. The non-linear k-e model performs well in 3D complex turbulent flows with flow separation and flow reattachment. The effect of angle of attack over flow structure, force coefficients and wall related flow variables are discussed in detail. Keywords: Computational Fluid Dynamics (CFD); Autonomous Underwater Vehicle (AUV); Reynolds averaged Navier-Stokes Equation (RANS); non-linear k-e turbulence model doi: http://dx.doi.org/10.3329/jname.v8i2.6984 Journal of Naval Architecture and Marine Engineering 8(2011) 149-163

22 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of control surfaces over the flow, the flow interaction between the hull and the appendages at various Angles of Attack (AoA), and the effects of the symmetry plane is studied.
Abstract: Three dimensional (3D) flow past an Autonomous Underwater Vehicle (AUV) is simulated using a Computational Fluid Dynamics (CFD) approach at a Reynolds (Re) number of 2.09x106. A non-linear k-e (NLKE) turbulence model is used for solving the Reynolds Averaged Navier-Stokes (RANS) equations. The effect of control surfaces over the flow, the flow interaction between the hull and the appendages at various Angles of Attack (AoA) and the effect of the symmetry plane is studied. Flow structure, variation of flow variables and force distribution for various AoA are presented and discussed in detail. DOI: http://dx.doi.org/10.3329/jname.v9i2.12567 Journal of Naval Architecture and Marine Engineering 9(2012) 135-152

3 citations


Cited by
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Journal ArticleDOI
01 Feb 2021
TL;DR: Autonomous underwater vehicles play an essential role in geophysical data collection, deep water mining, seafloor mapping, ocean exploration, and in many other related activities starting from mili... as mentioned in this paper.
Abstract: Autonomous underwater vehicles play an essential role in geophysical data collection, deep water mining, seafloor mapping, ocean exploration, and in many other related activities starting from mili...

37 citations

Journal ArticleDOI
TL;DR: In this article, experimental and numerical studies carried out in conjunction, to investigate the hydrodynamic characteristics of AUV hulls at different Reynolds numbers over sloped channel-beds are presented.
Abstract: Improved designs for Autonomous Underwater Vehicles (AUV) are becoming increasingly important due to their utility in academic and industrial applications. However, a majority of such testing and design is carried out under conditions that may not reflect the operating environment of shallow water AUVs. This may lead to imprecise estimations of the AUV's performance and sub-optimal designs. This article presents experimental and numerical studies carried out in conjunction, to investigate the hydrodynamic characteristics of AUV hulls at different Reynolds numbers over sloped channel-beds. We carry out experiments to measure the velocity field and turbulent statistics around the AUV with quantified uncertainty. These are contrasted against corresponding flat bed experiments to gauge the effect of test bed topography on AUV performance. The experimental data was used to validate Reynolds Stress Model predictions. Hydrodynamic parameters such as drag, pressure and skin friction coefficients were predicted from the RSM simulations at different test bed slopes, angles of attack and drift angles of the AUV hull, to analyze the hydrodynamic performance of the AUV. The results presented in this article offer avenues for design improvement of AUVs operating in shallow environments, such as the continental slope and estuaries.

27 citations

Journal ArticleDOI
TL;DR: In this paper, experimental and numerical studies on the effect of free stream turbulence (FST) on evolution of flow over an AUV hull form at three Reynolds numbers with different submergence depths and angles of attack.
Abstract: This article presents experimental and numerical studies on the effect of free stream turbulence (FST) on evolution of flow over an autonomous underwater vehicle (AUV) hull form at three Reynolds numbers with different submergence depths and angles of attack. The experiments were conducted in a recirculating water tank and the instantaneous velocity profiles were recorded along the AUV using Acoustic Doppler Velocimetry (ADV). The experimental results of stream-wise mean velocity, turbulent kinetic energy (TKE) and Reynolds stresses were used to validate the predictive capability of a Reynolds stress model (RSM) with the wall reflection term of the pressure strain correlation. From the high fidelity RSM based simulations it is observed that in presence of free stream turbulence, the pressure, skin friction, drag and lift coefficients decrease on the AUV hull. The variation of the hydrodynamic coefficients were also plotted along the AUV hull for different values of submergence depth and angle of attack with different levels of free stream turbulence. The conclusions from this experimental and numerical investigation give guidance for improved design paradigms for the design of AUVs.

25 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the hydrodynamic performance of an AUV, calculate its hydrodynamics coefficients, and consider the flow characteristics of underwater bodies, and conclude that a hull shape with bullet nose and sharp tail with length-to-diameter ratio (LTDR) equal to 7.14 performs better than the SUBOFF model.
Abstract: The main aims of this study are to investigate the hydrodynamic performance of an autonomous underwater vehicle (AUV), calculate its hydrodynamic coefficients, and consider the flow characteristics of underwater bodies. In addition, three important parts of the SUBOFF bare hull, namely the main body, nose, and tail, are modified and redesigned to improve its hydrodynamic performance. A three-dimensional (3D) simulation is carried out using the computational fluid dynamics (CFD) method. To simulate turbulence, the k–ω shear stress transport (SST) model is employed, due to its good prediction capability at reasonable computational cost. Considering the effects of the length-to-diameter ratio (LTDR) and the nose and tail shapes on the hydrodynamic coefficients, it is concluded that a hull shape with bullet nose and sharp tail with LTDR equal to 7.14 performs better than the SUBOFF model. The final proposed model shows lower drag by about 14.9% at u = 1.5 m·s−1. Moreover, it produces 8 times more lift than the SUBOFF model at u = 6.1 m·s−1. These effects are due to the attachment of the fluid flow at the tail area of the hull, which weakens the wake region.

21 citations

Journal ArticleDOI
01 Feb 2020
TL;DR: The results showed that all the autonomous underwater vehicle hulls designed in this study, at an attack angle of 0°, had a lower drag force than the autonomous submerged vehicle hull used for validation except geometry no. 1.
Abstract: In this research, the flow around the autonomous underwater vehicles with symmetrical bodies is numerically investigated. Increasing the drag force in autonomous underwater vehicles increases the e...

13 citations