Nonhomogeneous Flow Research Articles

Novel irreversibility modeling of non-homogeneous charged gas flow by solving Maxwell–Boltzmann PDEs system: irreversibility analysis for multi-component plasma

Novel irreversibility modeling of non-homogeneous charged gas flow by solving Maxwell–Boltzmann PDEs system: irreversibility analysis for multi-component plasma

Global existence and exponential decay of strong solutions to the 3D nonhomogeneous nematic liquid crystal flows with density-dependent viscosity

Global existence and exponential decay of strong solutions to the 3D nonhomogeneous nematic liquid crystal flows with density-dependent viscosity

Effect of the impeller blade outlet setting angle on the performance of the helical axial-flow multiphase pump

Effect of the impeller blade outlet setting angle on the performance of the helical axial-flow multiphase pump

Insight into the dynamics of bioconvective Walter’s-B nanofluid flow subjected to Cattaneo–Christov heat flux and activation energy

In order to study the implementation of the generalized magnetohydrodynamic (MHD) bioconvective aspects of the Walter’s-B fluid flows over a convectively heated stretched sheet in the presence of activation energy and numerous boundary conditions, the non-homogeneous nanofluid flow model is used. Here, the nonlinear differential equations illustrating the current nanofluid flow model of non-Newtonian fluid explicitly include the concentration of both motile microbes and solid nanoparticles. Furthermore, the associated temperature, impact of thermal radiation and the Cattaneo–Christov heat flux model are discussed. The similarity transformations are formally displayed to transfer the consequential reduction in the mathematical complexity of the existing physical situation by converting partial differential equations (PDEs) into a nonlinear associated framework of ordinary differential equations (ODEs). Furthermore, the homotopy analysis method (HAM) through the MATLAB tool is used to numerically solve the dimensionless similarity equations. The results are extremely well demonstrated. In this manner, the significant engineering procedures are more accurately and entirely estimated before being reported. The results of the fixed physical factors of velocity, temperature, concentration, and microbe concentration profiles are effectively demonstrated through multiple types of illustrations and comprehensive explanations. The principal assumption is that the greater significance of the bioconvection Lewis and Peclet numbers can lead to a drop in the microbe concentration profile. It is observed that the concentration profile is reduced with the greater value of the concentration relaxation parameter.

Lagrangian modeling of a nonhomogeneous turbulent shear flow: Molding homogeneous and isotropic trajectories into a jet

Lagrangian modeling of a nonhomogeneous turbulent shear flow: Molding homogeneous and isotropic trajectories into a jet

Sector orifice with a correlation-based analysis

In single and multiphase flows, an orifice is a vital flow-measuring and flow-controlling device that operates on Bernoulli’s theorem on the determination of the pressure drop (∆p). Laboratory, petroleum, energy, nuclear, mining, chemical, processing, and food industries all depend on flow monitoring and flow regulations. A sector or segmental orifice meter is a much simpler device used for drainage and sediment-laden type non-homogeneous flow. Sector orifice meter analysis is the rate of flow, pressure and velocity profile concerning input parameters to find out the ∆p and coefficient of discharge (Cd) of an orifice meter. The present study varies with different sector angles (θ), Reynolds number (Re) and space ratio (s/d) of the sector orifice for the flow analysis with the use of CFD (Ansys. Inc) based study. The numerical simulation range considered for θ (30°-180°), Re (10000-100000), and s/d (0.1-0.9). To compute the flow rate, ∆p and Cd by using air as a working fluid to present a flow problem through high viscous flow. The simulation also presents the pressure and velocity profiles along the flow on the variant of Re, θ and s/d. Based on the numerical data a correlation developed which will help the measurement through sector orifice for wide range of future application. With the comparison of the existing literature, this will give a good contribution to sector orifice for accurate flow measurement for high viscous flow.

Efficient passive GDQLL scrutinization of an advanced steady EMHD mixed convective nanofluid flow problem via Wakif–Buongiorno approach and generalized transport laws

Owing to the practical importance of nanofluids and their adjustable thermal capabilities, this study intends to develop a robust generalized differential quadrature local linearization (GDQLL) algorithm for examining realistically the heat and mass aspects of electrically conducting nanofluids during their non-Darcian laminar motion nearby a convectively heating vertical surface of an active electromagnetic actuator (i.e., Riga plate). By invoking Wakif–Buongiorno model and Oberbeck–Boussinesq approximations along with other generalized transport laws (i.e., Cattaneo–Christov and non-Fick’s laws) and Grinberg’s concept, a set of gigantic partial differential equations is stated appropriately in the sense of the boundary layer approximations for describing exhaustively the present EMHD mixed convective nonhomogeneous flow under the passive control strategy of nanoparticles within the nanofluidic medium. Operationally, the dimensionless differential forms of the governing boundary equations are derived properly by introducing reasonable mathematical adjustments into the preliminary formulation. In this case, the differential complexity of the leading differential structure is reduced to a nonlinear coupled system of ordinary differential equations, whose discrete numerical solutions are computed perfectly via a well-structured GDQLL algorithm. As foremost outcomes, it is demonstrated that the nanofluid motion and its surface thermal enhancement rate can be reinforced significantly through the thermal strengthening in the convective heating and mixed convective process as well as via the electromagnetic improvement in the driven aspect of Lorentz’s forces.

A sediment transport theory based on distortion-free-boundary nonhomogeneous fluid flows

Over the last 50 years several sediment transport models in coastal environments based on Shallow Water(SW) type models have been developed in the literature. The water flow over an abrupt moving topography quickly spatially variable becomes accelerated and strongly varied arising the turbulence (distortion). The acceleration and strong variation of the flow facilitate the transport of a large quantity of sediments present at the bottom while modifying it. The mathematical models based on SW type models widely used to describe the sediment transport phenomena do not account the distortion effects. Indeed, it is well-known that the SW models are derived from first order approximation of long wave theory. The acceleration and strong variation of the water flow near the bottom is due to the distortion of the horizontal velocity profile along the vertical direction. One can regard distortion as a combination of strain and rotation. The effect of the rotational component is to weaken the effect of the strain somewhat. In this work, we put in place a king theory of sediment transport derived from the second order approximation of long wave theory that can describe sediment transport processes in distortion-free-boundary nonhomogeneous fluid flows. The derived model accounts the distortion (fluctuation with great correlation lengths) that creates the turbulence. Moreover, the model differentiates the fluid velocity from sediment velocity (phase-lag) near the sediment bed. The proposed theory significantly reduces the modeling errors observed in several sediment transport models based on nonhomogeneous shallow water equations and has a great potential to increase the predictive power of sediment transport models in rivers, lakes, coastal flows, ocean basins and so on. The proposed theory improves several existing sediment transport theories recently developed in the literature and can be apply with some degree confidence.

Energy conservation of weak solutions for the incompressible Euler equations via vorticity

Motivated by the works of Cheskidov, Lopes Filho, Nussenzveig Lopes and Shvydkoy in [8, Commun. Math. Phys. 348: 129-143, 2016] and Chen and Yu in [5, J. Math. Pures Appl. 131: 1-16, 2019], we address how the Lp control of vorticity could influence the energy conservation for the incompressible homogeneous and nonhomogeneous Euler equations in this paper. For the homogeneous flow in the periodic domain or whole space, we provide a self-contained proof for the criterion ω=curlv∈L3(0,T;L3nn+2(Ω))(n=2,3), that generalizes the corresponding result in [8] and can be viewed as in Onsager critical spatio-temporal spaces. Regarding the nonhomogeneous flow, it is shown that the energy is conserved as long as the vorticity lies in the same space as before and ∇ρ belongs to L∞(0,T;Ln(Tn))(n=2,3), which gives an affirmative answer to a problem proposed by Chen and Yu in [5].

Steering undulatory micro-swimmers in a fluid flow through reinforcement learning.

This work aims at finding optimal navigation policies for thin, deformable microswimmers that progress in a viscous fluid by propagating a sinusoidal undulation along their slender body. These active filaments are embedded in a prescribed, non-homogeneous flow, in which their swimming undulations have to compete with the drifts, strains, and deformations inflicted by the outer velocity field. Such an intricate situation, where swimming and navigation are tightly bonded, is addressed using various methods of reinforcement learning. Each swimmer has only access to restricted information on its configuration and has to select accordingly an action among a limited set. The optimisation problem then consists in finding the policy leading to the most efficient displacement in a given direction. It is found that usual methods do not converge and this pitfall is interpreted as a combined consequence of the non-Markovianity of the decision process, together with the highly chaotic nature of the dynamics, which is responsible for high variability in learning efficiencies. Still, we provide an alternative method to construct efficient policies, which is based on running several independent realisations of Q-learning. This allows the construction of a set of admissible policies whose properties can be studied in detail and compared to assess their efficiency and robustness.

CFD Simulation and Optimization of the Leaf Collecting Mechanism for the Riding-Type Tea Plucking Machine

In the process of tea plucking and leaf gathering, the structure optimization design of the leaf collecting mechanism is the key element responsible for collecting fresh leaves. The unreasonable design and manufacture of leaf collecting mechanisms will cause the smooth collection of fresh leaves, the quality of the collected fresh leaves will be damaged, and the commodity value will be reduced. In order to further study the structural characteristics of the leaf collecting mechanism, an air outlet model of the leaf collecting mechanism was established for the phenomena of internal vortex rotation and impact in the leaf collecting mechanism process. The internal flow field of the leaf collecting mechanism, the movement trajectory of fresh leaves, and the non-homogeneous flow are calculated using computational fluid dynamics (CFD). Based on Box-Behnken’s central combinatorial design theory, the velocity inlet and outlet air structure factors are taken as the influencing factors to carry out response surface test research. The effect of different parameters such as engine rotation, shape of the blowing cavity and air outlet parts, and velocity on the flow is determined. The optimal parameter combination is as follows: the height of the outlet end, the length of the inlet end, and the velocity inlet are 0.01 m, 0.03 m, and 25 m/s, respectively. Furthermore, it was found that when the number of plates increases from 1 to 4, the non-homogeneity decreases all the time, and the distribution of blowing air is improved without a sharp decrease in velocity. The average velocity outlet was larger than the velocity inlet, which meets the requirements of blade gathering. Considering comprehensively, the flow field simulation of the blade collecting mechanism with four baffles was consistent with the test results of the velocity outlet. The validation results showed that the model can successfully simulate the air flow inside the leaf-collecting mechanism, and the reasonable structure design was conducive to reducing the number of collisions between tea buds and improving the quality of tea buds. This research has certain theoretical and practical implications for the accurate plucking of high-quality tea.

Abstract 1428: Luminescent immunoassays for homogeneous determination of cell proliferation and senescence

Abstract We have developed homogeneous, luminescent immunoassays for simple and rapid determination of Ki-67 and uPAR levels in 96-well format, thereby enabling efficient and quantitative assessment of proliferation and senescence in mammalian cell culture. Assessment of proliferative capacity is of key importance in numerous research areas, including cancer and various proliferative disorders, assessment of cell fitness (e.g., T cell fitness, stem cell characterization), and evaluation of test compound or drug effects. Cell senescence, characterized in part by loss of proliferative capacity, is an altered, proinflammatory state of cells induced in response to developmental ques, aging, disease, or acute stressors typically involving DNA damage. Ki-67 is a nuclear protein widely used as a marker of proliferation due to its pervasive expression in cycling cells but absence from non-dividing (G0) cells, whether quiescent, senescent, or terminally differentiated. In contrast, urokinase plasminogen activator receptor (uPAR) is a cell-surface protein whose expression was recently reported to increase significantly with the induction of senescence. Of note, commonly used assays of Ki-67 and uPAR levels typically rely upon non-homogeneous methods, including imaging, flow cytometry, or western blotting. Application of Lumit™ technology enabled our development of no-transfer, no-wash immunoassays for Ki-67 (lytic) and uPAR (nonlytic) determinations directly in cell wells. Treatment of human CD8+ T cells with CD3/CD28 T cell activator produced more than a 10-fold upregulation of Ki-67 levels, consistent with induction of T cell proliferation. In contrast, treatment of HCT116 colorectal cancer cells for 48 h with the antiproliferative compounds doxorubicin (100 nM) and nutlin-3A (10 μM) produced 65% and 90% reductions, respectively, in Ki-67 levels normalized to a measure of viable cell number, consistent with their relative antiproliferative activities. Dose-dependent treatment of HCT116 cells with nutlin-3A for 24 and 48 h produced 69% and 93% reduction, respectively, in normalized Ki-67 levels with a potency of ~2.5 μM. Treatment of HCT116 and A549 cancer cell lines for 72 h with 10-20 μM nutlin-3A, in addition to causing profound reduction in Ki-67 levels and loss of proliferative capacity, produced 2.3- to 4-fold increases in cell-surface uPAR levels, reflective of the emergence of the senescence phenotype. These luminescent, homogeneous Ki-67 and uPAR immunoassays provide an efficient means to quantitatively assess changes in cell proliferation and senescence in cell culture models for basic research and drug discovery applications. Citation Format: Dan F. Lazar, Kevin R. Kupcho, Andrew L. Niles, James J. Cali. Luminescent immunoassays for homogeneous determination of cell proliferation and senescence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1428.

Profiling cross-sectional area of a radial rotating detonation combustor to increase pressure gain

The detonation wave(s) in a rotating detonation combustor (RDC) produce highly unsteady flow with varying supersonic and subsonic segments. The non-homogeneous RDC flow must be conditioned to improve its uniformity, which can increase the performance and operation of the downstream hardware for propulsion and power generation applications. In this study, the RDC channel and converging nozzle are combined into a single flow conditioning device, and Gradual to rapid (GTR), Linear, and Rapid to Gradual (RTG) strategies to profile the cross-sectional area of the combined channel are introduced. An inward flowing disk-RDC (D-RDC) operated on gaseous methane-oxygen is numerically investigated using a quasi-two-dimensional computational fluid dynamic (CFD) simulation with a curvilinear coordinate system. The study focuses on the combined channel to isolate the effects of area profiling and neglects radial to axial turning of the flow necessary to integrate it, for example, with an aerospike nozzle located downstream. Simulations show that the RTG area profile yields a higher performance compared to GTR and Linear cases. The RTG profile is also shown to improve pressure and temperature uniformity of the RDC flow at the throat. Results are analyzed to show that a rapid decrease in the cross-sectional area closer to the detonation for the RTG profile improves the stability of the detonation process and constrains the expansion of product gases behind detonation to orient the flow radially inwards. Therefore, profiling the cross-sectional area of an RDC can be vital in improving the operability and effective integration of the downstream hardware.

Numerical passive control of alumina nanoparticles in purely aquatic medium featuring EMHD driven non-Darcian nanofluid flow over convective Riga surface

Motivated by the thermal importance of feeble electrically conducting nanofluids and their flow controls in many industrial and engineering applications, the present scrutinization intended to evidence comprehensively the main electro-magneto-hydrothermal and mass aspects of convective non-homogeneous flows of alumina-based purewater nanofluids Al2O3-H2O over a horizontal flat surface of an electromagnetic actuator (i.e., Riga pattern, which is embedded geometrically in a Darcy-Forchheimer porous medium. Further, the present nanofluid flow model is formulated realistically under the umbrella of the renovated two-phase Buongiorno’s approach with the inclusion of Brownian motion and thermophoresis diffusive phenomena, in which the vertical component of the nanoparticles’ mass flux tend to vanish at the limiting contact surface due to its impermeability trend. For streamlining the technical handling of the present nanofluid flow problem, the governing partial differential equations (PDEs) are simplified mathematically by adopting the physical approximations of the boundary layer theory and then transformed into a differential structure of ordinary differential equations (ODEs) based on several similarity changes. Methodologically, the resulting nonlinear coupled ODEs are solved numerically via a validated differential quadrature procedure. Besides, the generated graphical demonstrations show that the nanofluid temperature is enhanced significantly with the porosity factors, the nanoparticles’ loading, the convective heating strength, and the thermophoresis process. However, the porosity factors and the nanoparticles’ loading exhibit a slowing-down impact on the nanofluid motion. Usefully, it is revealed from the obtained GDQM - NRT datasets that the nanoparticles’ loading and the porosity factors express an important improvement in the strength of the surface viscous drag forces, whereas the induced electromagnetic field shows a reverse viscous frictional impact.

Hydrothermal and mass aspects of MHD non-Darcian convective flows of radiating thixotropic nanofluids nearby a horizontal stretchable surface: Passive control strategy

Numerous rheological examinations attested that many products employed frequently in our daily life exhibit a thixotropic rheological behavior with a shear-thinning tendency (e.g., toothpaste, hair gels, ketchup, gypsum, and paints). Motivated by the importance of nanofluids in the thermal and mass transfer processes and their rheological trends, this article aimed to analyze convective boundary layer flows of radiating thixotropic nanofluids over a horizontal stretching surface by considering the retardational influences of Darcy-Forchheimer and Lorentz forces and invoking the effective contribution of Brownian and thermophoresis diffusions in the energy and concentration equations. By adopting the boundary layer approximations along with the zero mass flux and convective conditions, the conservation equations of the present non-homogeneous nanofluid flow model are derived mathematically in the form of partial differential equations (PDEs) based on Buongiorno's approach. After converting the leading PDEs into a set of nonlinear coupled ordinary differential equations (ODEs) via feasible local similarity alterations, the resulting highly nonlinear system of governing ODEs is then solved numerically using an efficient differential quadrature algorithm. As findings, it is found that the thixotropy feature reinforces the nanofluid motion. Besides, the significant impact of the radiative term is noticed in the heat flux rate. In contrast, the induced Darcy-Forchhemier and Lorentz forces impact unfavorably on the nanofluid flow and consequently alter the intensity of drag forces. Further results are provided also graphically and tabularly.

Flow-concentration coupling determines features of nonhomogeneous flow and shear banding in entangled polymer solutions

Shear banding in entangled polymer solutions is an elusive phenomenon in polymer rheology. One recently proposed mechanism for the existence of banded velocity profiles in entangled polymer solutions stems from a coupling of the flow to banded concentration profiles. Recent work [Burroughs et al., Phys. Rev. Lett. 126, 207801 (2021)] provided experimental evidence for the development of large gradients in concentration across the fluid. Here, a more systematic investigation is reported of the transient and steady-state banded velocity and concentration profiles of entangled polybutadiene in dioctyl phthalate solutions as a function of temperature (T), number of entanglements (Z), and applied shear rate (Wiapp), which control the susceptibility of the fluid to unstable flow-concentration coupling. The results are compared to a two-fluid model that accounts for coupling between elastic and osmotic polymer stresses, and a strong agreement is found between model predictions and measured concentration profiles. The interface locations and widths of the time-averaged, steady-state velocity profiles are quantified from high-order numerical derivatives of the data. At high levels of entanglement and large Wiapp, a significant wall slip is observed at both inner and outer surfaces of the flow geometry but is not a necessary criterion for a nonhomogeneous flow. Furthermore, the transient evolution of flow profiles for large Z indicate transitions from curved to “stair-stepped” and, ultimately, a banded steady state. These observed transitions provide detailed evidence for shear-induced demixing as a mechanism of shear banding in polymer solutions.

Evaluation of constitutive models for shear-banding wormlike micellar solutions in simple and complex flows

Wormlike micellar solutions possess complex rheology: when exposed to a flow field, the wormlike micelles may orientate, stretch, and break into smaller micelles. Entangled wormlike micellar solutions exhibit shear banding characteristics: macroscopic bands with different local viscosities are organized and stacked along the velocity gradient direction, leading to a non-monotonic flow curve in simple shear. We present a systematic analysis of four commonly used constitutive models that can predict a non-monotonic flow curve and potentially describe the rheology of entangled wormlike micellar solutions with shear-banding characteristics: the Johnson–Segalman, the Giesekus, the thixotropic viscoelastic, and the Vasquez–Cook–McKinley (VCM) models. All four constitutive models contain a stress diffusion term, to account for a smooth transition between the shear bands and ensure a uniqueness of the numerical solution. Initially, the models are fitted to shear and extensional experimental data of a shear-banding wormlike micellar solution. Subsequently, they are employed to solve three non-homogeneous flows: the Poiseuille flow in a planar channel, the flow in a cross-slot geometry, and the flow past a cylinder in a straight channel. Each of these flows exposes the wormlike micellar solution to different flow kinematics (shear, extensional, and mixed), revealing different aspects of its rheological response. The predictive capability of each model is evaluated by directly comparing the numerical results to previously published experimental data obtained from microfluidic devices with corresponding flow configurations. While all the models can describe qualitatively the characteristic features observed experimentally in the benchmark flows, such as plug-like velocity profiles and elastic instabilities, none of them yields a quantitative agreement. Based on the overall performance of the models and also accounting for their differing numerical complexity, we conclude that the Giesekus model is at present the most suitable constitutive equation for simulating shear banding wormlike micellar solutions in flows that exhibit both shear and extensional deformations. However, the quantitative mismatch between model predictions and experiments with wormlike micellar solutions demand that improved constitutive models be developed in future works. • Comparison of popular constitutive models for wormlike micellar solutions. • Evaluation of their performance in rheometric and inhomogeneous shear flows. • Investigation of their predictions in extensional flows and elastic instabilities. • The models can only make qualitative predictions.

Decay properties for a density-dependent liquid crystal system

The purpose of this paper is to establish the optimal temporal decay properties for nonhomogeneous incompressible liquid crystal flows in Rn, n = 2, 3. Under a weaker smallness assumption on the initial datum d0, we construct a uniform (in t) energy estimate for the director field d, which plays a crucial role in giving the optimal L2-decay rates for the liquid crystal flows. If the initial data are more regular, the optimal decay rates for the higher spatial derivatives are also obtained.

The effect of solute release position on transient solute dispersion in floating wetlands: An analytical study

Considering the stochastic and complex pollutant emissions in the application of floating wetlands, we investigate the effects of release position on the solute transport in this work. On the basis of the analytical expressions derived from concentration moments, the temporal evolutions of dispersion intensity, the cloud distortion, and the displacement of the cloud centroid at the preasymptotic stage are all analyzed. Owing to the nonhomogeneous flow field, the location of the point source determines the strength of the initial advection, diffusion, and velocity shear acting on a solute cloud, which in turn affects the dispersion process. As a result, the waiting time before the dispersion enters the anomalous regime, the dispersion mechanism, the normality of mean concentration distribution, and the form of spatial concentration distribution are all influenced by the initial condition. The time at which the Taylor dispersion model is capable to depict the mean concentration distribution is t = 0.3 for the line source case and t = 0.5 for point sources released in the outer shear layer, and t = 1 for point sources released in the canopy region and the bottom boundary layer. The point source releases below the internal canopy layer and the line source release cause the initial accumulation of solute in the bottom boundary layer, even for the cases with relatively strong longitudinal dispersion. The depende-

Cauchy problem for the Navier–Stokes–Voigt model governing nonhomogeneous flows

Cauchy problem for the Navier–Stokes–Voigt model governing nonhomogeneous flows