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The ecology of marine life and other biotic processes, such as septicity, are influenced by the drive of microorganism cells in the fluid. Considering the transference mechanism in nanofluids including a microbial suspension is imperative for several chemical and medical applications. This study examines the bioconvection of an Al₂O₃-Graphene-CNT/water ternary hybrid nanofluid between two infinitely parallel spinning disks in a porous media under the influence of heat source/sink and radiation. The Cattaneo–Christov model has been employed to inspect the transference mechanism of mass and heat. The MATLAB function “bvp4c” is used to numerically tackle the governing equations. The relationship between the most relevant variables and the motile microorganism’s density, velocity, temperature, concentration of nanoparticles and other characteristics is graphically represented. Last, figures are provided to illustrate how several important elements relate to the Nusselt and Sherwood number, and local motile microbe density number. The heat transfer rate is seen to be higher at the upper disk than at the lower disk. A rise in the volume fraction of nanoparticles causes the heat transfer rate at both disks to increase. The outcomes of this study will be useful for a wide range of architectural designs, transportation systems, oil recovery systems with microbes, medical sectors and other industries that utilize nanofluids.

Flow of fluids between rotating surface is encountered in many industrial, manufacturing, mixing and biological processes. These fluids are complex, exhibit various rheological characteristics, and thus follow highly nonlinear models. In this paper, we have used fourth grade fluid model to represent fluids involved in such processes. The steady flow between two coaxial rotating disks is modeled. The resulting highly nonlinear equations are solved using perturbation approach. The velocity field in three-dimensional cylindrical coordinate system is reported. The results are then simulated to present a visual understanding of the flow.

This paper is concerned with the thermoelastic analysis of a functionally graded rotating annular disk subjected to a nonuniform steady-state thermal load. Material properties are assumed to be temperature independent and continuously varying in the radial direction of the annular disk. The variations of Young's modulus, material density, thermal expansion and conductivity coefficients are represented by a novel exponential-law distribution through the radial direction of the disk, but Poission's ratio is kept constant. The governing differential equations are exactly satisfied at every point of the disk. Exact solutions for the temperature and stress fields are derived in terms of an exponential integral and Whittaker's functions. Presented are some results for stress, strain and displacement components due to thermal bending of the rotating disk. The effects of angular velocity, inner and outer temperature loads and material properties on the stress, strain and displacement components are discussed.

In this paper, the dynamic stability of a disk rotating in air has been modeled and analyzed numerically as well as observed from experiments. A simple expression on the aerodynamic loading acting on the rotating disk is applied in the modeling, and the dynamic stability results of the disks are evaluated based on the eigenvalues for the vibration modes. The disk critical speeds and the flutter speeds are calculated and compared with the results from experiments, which are conducted on two steel disks with different diameters and thicknesses. The modeling predicts that the rotating disk flutter starts with the mode (0, 3)B, which agrees with the results reported in the literature and the observation in the present experimental study.

An analytical method is presented for determination of vibration characteristics of high speed Double-Segment Compound Rotating disks. More specifically, a systematic approach based on established solution for linear in-plane vibration of each segment satisfying the displacement and stresses compatibility is developed. Fixed and free boundary conditions for the compound spinning annular disks are considered, and natural frequencies and mode shapes of rotating the disks are computed. The medium for each segment is considered to be homogenous, isotropic, and elastic. The developed analytical solution was achieved by implementing two-dimensional plane stress theory. The modal displacements and stresses at both inner and outer boundaries are determined. The dimensionless natural frequencies for different modes, rotating speeds, and thickness ratios are computed. The effect of stiffness changes for each segment on the natural frequencies are also studied.