Faculty Publications
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Item Investigation of steady state rheological properties and sedimentation of coated and pure carbonyl iron particles based magneto-rheological fluids(Elsevier Ltd, 2020) Swaroop, K.V.; Aruna, M.N.; Kumar, H.; Rahman, M.R.MR fluids face a major problem of sedimentation rate due to the high- density difference between the magnetic particles and the carrier medium that affects the performance of the magnetorheological devices. In this work, two MRF samples are prepared, where MRF-1 and MRF-2 are pure and coated carbonyl iron particles (CIPs) based MR fluids. The surface modification of the CIPs is performed using the solvent dispersion method to improve the sedimentation rate. The spherical shape and particle size analysis of the pure CIPs and coated CIPs' morphology is investigated using the Scanning Electron Microscope (SEM). The Thermal Gravimetric Analysis (TGA) shows that the coated CIPs have high thermal stability and confirm that 6% by wt. coating is present in the coated sample. The chemical bonding of the coated CIPs is detected using the Fourier Transform Infrared Spectroscopy (FT-IR). The saturation magnetization (Ms) of pure and coated CIPs is 245 emu/g and 120 emu/g, respectively, at 15 kOe, which is obtained by using a superconducting quantum interface device (SQUID). The rheology flow curve properties show that MRF-1 and MRF-2 exhibit yield stress of about 10 kpa and 9 kpa, respectively, for varying magnetic fields ranging from 0 to 343 kA/m. The Herschel-Bulkley model is fitted with the experimental data and the shear thinning behaviour is observed for both MR fluids. The sedimentation study shows that MRF-2 has better settling rate than MRF-1, which is observed by using the visual observation method up to 600 h. © 2020 Elsevier Ltd. All rights reserved.Item Nearshore waves and longshore sediment transport along Rameshwaram island off the east coast of India(Society of Naval Architects of Korea jnaoe@jnaoe.org, 2015) Gowthaman, R.; Sanil Kumar, V.; Dwarakish, G.S.; Shanas, P.R.; Jena, B.K.; Singh, J.Wave-induced Longshore Sediment Transport (LST) play an important role in the dynamics of the Dhanushkodi sandspit located southeast of Rameshwaram. The LST along the Dhanushkodi coast is studied based on data collected simultaneously in Gulf of Mannar (GoM) and Palk Bay (PB) using directional waverider buoys. The numerical model REF/DIF1 was used to calculate the nearshore waves and the LST rate was estimated using three different formulae. The model validation was done based on the measured nearshore waves using InterOcean S4DW. Numerical model LITPACK was also used for simulating non-cohesive sediment transport and the LITLINE module was used to study the shoreline evolution over 5 years. Low net annual LST along PB (~ 0.01×106 m3) compared to the GoM region (0.3×106 m3) were due to the weak waves. Accretion in the region led to growth of the Dhanushkodi sandspit by 65 m during the period 2010-2015. © SNAK, 2015.Item Influence of additives on the synthesis of carbonyl iron suspension on rheological and sedimentation properties of magnetorheological (MR) fluids(Institute of Physics Publishing helen.craven@iop.org, 2019) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumar, H.Magnetorheological (MR) fluid is one of the major constituent element in structural suspensions and damping characteristic in automobile applications. The major drawback is sedimentation in MR fluids, in the present study an attempt has been done to address the sedimentation issue. The synthesis and characterization of MR fluid in combination with clay and additives leads to improvement in sedimentation rate. The four different types of MR fluid were prepared in combination with clay, friction reducing agent and poly-alpha-olefin (PAO) oil naming as MRFp-1, 2, 3 and 4 as tabulated in table 1. The cost effective MRFp-3 shows better result compared to commercially available MR fluid with respect to off/on state shear stress, viscosity. It is also observed that in-house prepared MRFp-3 has better sedimentation than commercially available (LORD-132DG) up to 700 h. © 2019 IOP Publishing Ltd.Item Investigation of sedimentation, rheological, and damping force characteristics of carbonyl iron magnetorheological fluid with/without additives(Springer, 2020) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumar, H.In the present study, the magnetorheological fluid (MRF) samples are prepared using pure carbonyl iron particles (CIPs), CIPs/Claytone APA/Molyvan 855 additive, and friction reducer dispersed in poly-alpha-olefin oil. The scanning electron microscopy reveals that the Claytone additive morphology looks like a surface abundant in small folds, which connect the gaps between the spherical pure CIPs and prevent sedimentation in the MRF. The magnetic saturation properties are investigated through the vibrating sample magnetometer. The pure CIPs MRF shows (Ms) value as 146.12 emu/g, and the CIPs/Claytone APA/Molyvan indicates (Ms) as 55.12 emu/g. The magnetorheological flow curves, such as shear stress and viscosity as a function of shear rate, are investigated for the MRF samples through the magnetorheometer. The sedimentation analysis of the MRF is observed by visual inspection and shows that the CIPs/Claytone APA/Molyvan improved the sedimentation rate than the pure CIPs MRF. Finally, the experimental characterization of the prototype monotube MR damper is carried out using the hydraulic dynamic testing machine at 1.5 Hz frequency for damper peak–peak displacement length of ± 5 mm at three intervals of 0 h, 24 h, and 72 h in damper to know the effect on damping force for the prepared MRF samples against the sedimentation rate. © 2020, The Brazilian Society of Mechanical Sciences and Engineering.Item Computational modeling of hydrodynamics and mixing in a batch stirred vessel(Taylor and Francis Ltd., 2021) Falleiro, L.H.; Ali, A.A.In this work, the hydrodynamics, mixing and sedimentation is numerically investigated in the batch stirred vessel through CFD. The flow field obtained by performing transient CFD simulations using multiple reference frame (MRF) and sliding mesh approach along with standard k-? turbulence model. The velocity field is investigated spatially and temporally and liquid circulation is quantified at various impeller speeds to find an optimum impeller speed. The importance of geometry of the draft tube baffles is investigated by quantifying the vorticity, mixing time, power requirement and quality of suspension in the batch stirred vessel. It is found that suspension quantity in a batch stirred vessel is strongly dependent on the hydrodynamics. The role of the draft tube and the inner baffles is further analyzed and found that proper positioning and length of the baffles is necessary to improve the turbulence characteristics and the quality of the suspension. © 2019 Taylor & Francis Group, LLC.Item Influence of different fumed silica as thixotropic additive on carbonyl particles magnetorheological fluids for sedimentation effects(Elsevier B.V., 2021) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumar, H.; Bhat Panemangalore, D.B.The present work reports the influence of different types of surface area, hydrophobic, and hydrophilic fumed silica mixed in silicone oil as a thixotropic additive on carbonyl particles based magnetorheological fluids (MRFs) were prepared. Scanning electron microscopy analysis confirms the fumed silica particles attached to the surfaces of CIPs. The vibrating sample magnetometer result shows the MRF4 and 5 have a better magnetic saturation value of 30.12 emu/gm and 40.12 emu/gm, respectively. The experimental rheological flow curve behaviours are investigated using the magnetorheometer. The Herschel–Bulkley rheological model is found to be in good agreement with the experimental curves and suggested shear thinning property is observed. The results showed that the hydrophilic silica with larger surface area type presented (i.e.MRF 4 and 5) better magnetorheological fluid characteristics in terms of shear stress, with a high value of dynamic yield stress, and have much-improved sedimentation ratio up to seven days. © 2021 Elsevier B.V.Item Effect of temperature on sedimentation stability and flow characteristics of magnetorheological fluids with damper as the performance analyser(Elsevier B.V., 2022) Kumar Kariganaur, A.; Kumar, H.; Arun, M.dimentation stability and high yield stress of a magnetorheological fluid (MRFs) are essential parameters for better damping performance for any practical application. Preliminary investigations have been carried out on carbonyl iron particles to determine the morphology, particle size, crystal structure, and saturation magnetization for their feasibility of synthesizing magnetorheological fluids in-house. This study synthesizes various MRFs from various commonly used carrier oils and additives. The MRF samples were prepared for 25% volume fractions of carbonyl iron (CI) powder in either silicone oil (350cSt) or hydraulic oil (50cSt) and by using lithium and calcium-based additives or a combination of both the additives. The sedimentation stability and yield behaviour at different temperatures show a remarkable drop in sedimentation rate and yield stress for all the MR fluid samples. The characterization of the prepared MR fluids reveals that MRF-1, MRF-3, MRF-5 are more stable and have high yield stress values. MRF-1 is selected to further characterize its dynamic performance in magnetorheological damper fabricated based on geometric dimensions obtained from the response surface optimization technique. The results indicate a 164.45% and 135.48% increase in damping force at higher amplitude and higher frequencies at 0A and 1A currents. Further, similar tests have been carried out by synthesizing MRF-7 with silicone oil (50cSt) + lithium base grease as the additive. The sample's stability and yield stress with temperature are carried out, and performance analysis shows a remarkable change in damping force than MRF-1. The dynamic range obtained is practically viable in MRF-7 than MRF-1, with less variability. Finally, temperature characteristics captured from the thermocouple of the MR damper reveal that an average of 43.78% reduction in damping force when the temperature is increased by 19.5 °C with increased dynamic range. © 2022 Elsevier B.V.Item A study on magnetorheological and sedimentation properties of soft magnetic Fe58Ni42 particles(Elsevier B.V., 2022) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumara, H.; Meena, S.S.; Sarkar, D.; Umesh, C.K.In this study, the samples with two volume fractions (ϕ) of Fe58Ni42 (permalloy) i.e. (ϕ1 = 25 and ϕ2 = 30 %) were used as magnetic particles, silicone oil as a carrier fluid, and aluminium disterate as an additive. As received Fe58Ni42 particles surface morphology and composition of the Fe58Ni42 were investigated using field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS), respectively. The X-ray Diffraction (XRD) structural information analysis confirmed Fe58Ni42 particles have a face-centered cubic phase, corresponding with the result of the high resolution transmission electron microscopy (HRTEM) characterization technique. The magnetorheological properties were tested via rotational rheometer at four different magnetic field strengths. The results show that sample PMRF-30 has a maximum shear stress, shear viscosity, and dynamic modulus greater than the PMRF-25 sample. In addition, experimental shear stress flow curves are well fitted with Herschel-Bulkley rather than Bingham and Casson rheological models. The permalloy based magnetorheological fluid (PMRF) samples were prepared with a 25 % volume fraction and a 30 % volume fraction of permalloy particles with a sample abbreviation of PMRF-25 and PMRF-30, respectively. Furthermore, the sedimentation stability of suspensions of both the samples was observed using visual inspection. This method result shows the sedimentation ratio with respect to time of 72 h was 31 % and 29 %, respectively. © 2022 Elsevier B.V.Item Effect of reduced geometric dimensions on torque generation in two plate rotor magnetorheological brake with in-house magnetorheological fluid(Institute of Physics, 2023) Kariganaur, A.K.; Kadam, S.; Kumar, H.; Arun, M.The present study is aimed to evaluate the torque generation capacity of a two plate rotor magnetorheological (MR) brake using in-house prepared MR fluid. The prepared MR fluids were studied for sedimentation rate at different temperatures and flow characterization at different currents and at specific temperatures. The yield stress of the fluid is explored through Herschel-Bulkley model. The results depict significant increase in sedimentation rate and decrease in yield stress with increase in temperature of the MR fluid. MR brake (model-1) is fabricated after finite element method magnetics exhibit magnetic field of approximately 0.145 T in the shear gap than other two models (model-2 and model-3) considered in this study. Characterization of the MR brake illustrates that there is an increase in torque with increasing current. Further tests have been carried out to identify the effect of sedimentation on torque generation at 52 °C after 15 h of sedimentation. The results indicate 16% reduction in the initial torque because of settling of particles. MR fluid and particles characterization illustrates that 322 °C and 400 °C are critical points in controlling the MR fluid input parameters. © 2023 IOP Publishing Ltd.Item Study on operational temperature of magneto-rheological fluid and design dimensions of magneto-rheological damper for optimization(Institute of Physics, 2024) Kumar Kariganaur, A.; Kumar, H.; Arun, M.This study aims to restrict the upper limit for flow gap and effective length in magnetorheological (MR) damper for optimal performance. Initially, the sedimentation study of in-house MR fluid (25%) shows that an 8% reduction in the sedimentation ratio with the addition of additive and nonlinear Herschel-Bulkley (HB) model fit reflects a 32.5% decrease in average yield stress with increasing currents when the parallel plate gap is increased from 1 mm to 2 mm. Owing to this decrease in yield stress, further study is extended to fabricate two MR dampers with limit values (LV) of flow gap and effective length with a common magnetic outer cylinder. Testing results of MR dampers revealed a 72% reduction in damping force at 0.8 A current when the LV’s is increased from LV-1 to LV-2. Selecting LV-1 over LV-2 as the upper limit for any design optimization will give the MR damper optimal performance. At higher input parameters, amplitude has a 135% greater impact on damping force than frequency and current. It is also demonstrated that saturation magnetization depends on the applied magnetic field and input loading parameters. Finally, gravimetric analysis shows that the effectiveness of the MR fluid and magnetic particle starts to decline after 322 °C and 400 °C. © 2024 IOP Publishing Ltd.