Faculty Publications

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Publications by NITK Faculty

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Subject: search.filters.subject.Boundary layer flow

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    Influence of mixed convection in an exponentially decreasing external flow velocity
    (Elsevier Ltd, 2017) Patil, P.M.; Ramane, H.S.; Roy, S.; Hindasageri, V.; Momoniat, E.
    This article explores the influence of mixed convection in a steady incompressible laminar boundary layer flow for an exponentially decreasing free stream velocity in presence of surface mass transfer and heat source or sink. The nonlinear partial differential equations governing the flow and thermal fields are expressed in dimensionless form with the help of suitable non-similar transformations. The mathematical complexities in obtaining non-similar solutions at the leading edge of the streamwise coordinate as well as non-similarity variable ? have overcome by using the implicit finite difference scheme in conjunction with Quasi-linearization technique by choosing an appropriate finer step sizes along the streamwise direction. The effects of various dimensionless physical parameters on velocity and thermal fields are analysed. © 2016 Elsevier Ltd
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    Effect of RIBS/FINS and Aspect Ratio on Flow Boiling Characteristics in Conventional Channels
    (American Society of Mechanical Engineers (ASME), 2024) Madan, K.; Sathyabhama, A.
    In this work, experiments are conducted with conventional rectangular channels of two different aspect ratios (AR =w/d) for the horizontal boiling flow conditions at atmospheric pressure. Distilled water was used as the working substance. The heat transfer coefficients (HTC) were measured for mass fluxes and heat fluxes ranging from 85.94 kg/m2-s to 343.77 kg/m2-s and 10 kW/m2 to 100 kW/m2, respectively, and at inlet subcooled temperatures of 303 K, 313 K, and 323 K. Visualization of the boiling phenomenon was done using a high-speed camera for the two channels under similar conditions. The results show that the AR has a dominant effect on the HTC. At low heat flux values, higher HTC was noticed for the channel of higher AR (AR=1.25) whereas, at high heat flux conditions, the HTC is higher for the channel of lower AR (AR =0.2). With an increase in inlet subcooled temperature, the HTC decreased for both channels due to increased thermal boundary layer thickness and reduced bubble formation. Further, the channel of AR=1.25 with ribs/fins performed better than the smooth channel due to the high bubble nucleation rate. © 2023 by ASME.
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    Bursting phenomenon in turbulent wall-bounded flows
    (American Institute of Physics, 2025) Raghuram, S.; Ramesh, O.N.
    The scaling of bursting period governing the near-wall turbulence production in a wall-bounded flow has been an unresolved issue in the literature, despite nearly half a century of intense research. By using measurements from a turbulent channel flow along with laboratory boundary layer and atmospheric boundary layer data available in the literature, the appropriate scaling for the inter-burst time period (time period between two consecutive bursting events) is reexamined. The bursting period, non-dimensionalized using the inner scales, varied by five orders of magnitude over the Reynolds number range of 10 3 ? 10 7 , conclusively demonstrating thereby that the bursting period does not scale on inner variables. The bursting period, non-dimensionalized using the traditional outer timescale (ratio of the channel half-height to the centerline velocity), was found to asymptote to an invariant value at high Reynolds number for laboratory boundary layer and channel data. However, when the atmospheric boundary layer data were also included, this non-dimensional timescale's invariance became weaker and showed a slowly increasing trend with Reynolds number. A new modified outer timescale, where the friction velocity is the velocity scale, resulted in invariance for Reynolds number greater than 900 and suggests possible invariance over a wider range extending to higher Reynolds numbers. The new timescale is also amenable to a simple physical interpretation as the time of transit of the up-welling eddy to reach the outer region of the boundary layer/centerline of the channel flow. © 2025 Author(s).