Abstract Solutal convection in porous media is thought to be controlled by the molecular Rayleigh number, R a m , ratio of buoyant driving force over diffusive dissipation. The mass flux should increase linearly with and finger spacing decrease as . Instead, our experiments find that levels off at large increases Here we show convective pattern dispersive d balancing buoyancy dispersion. Increasing bead size medium but decreases hence coarsens pattern. While predominantly anisotropy...

A systematic investigation of unstable steady-state solutions the Darcy–Oberbeck–Boussinesq equations at large values Rayleigh number $\mathit{Ra}$ is performed to gain insight into two-dimensional porous medium convection in domains varying aspect ratio $L$ . The steady convective states are shown transport less heat than statistically ‘turbulent’ flow realised same parameter values: Nusselt $\mathit{Nu}\sim \mathit{Ra}$ for turbulent convection, while \mathit{Ra}^{0.6}$ maximum...

Steady two-dimensional Rayleigh--B\'enard convection between stress-free isothermal boundaries is studied via numerical computations. We explore properties of steady convective rolls with aspect ratios $\pi/5\le\Gamma\le4\pi$, where $\Gamma$ the width-to-height ratio for a pair counter-rotating rolls, over eight orders magnitude in Rayleigh number, $10^3\le Ra\le10^{11}$, and four Prandtl $10^{-2}\le Pr\le10^2$. At large $Ra$ are dynamically unstable, computed display $Ra \rightarrow \infty$...

We investigate the effect of hydrodynamic dispersion on convection in porous media by performing direct numerical simulations (DNS) a two-dimensional Rayleigh-Darcy domain. Scaling analysis governing equations shows that dynamics this system are not only controlled classical number based molecular diffusion, Ram, and domain aspect ratio, but also two other dimensionless parameters: dispersive Rayleigh Rad=H/αt dispersivity ratio r=αl/αt, where H is height αt αl transverse longitudinal...

The central open question about Rayleigh–Bénard convection – buoyancy-driven flow in a fluid layer heated from below and cooled above is how vertical heat flux depends on the imposed temperature gradient strongly nonlinear regime where flows are typically turbulent. quantitative challenge to determine Nusselt number $Nu$ Rayleigh $Ra$ $Ra\to \infty$ limit for fluids of fixed finite Prandtl $Pr$ spatial domains. Laboratory experiments, numerical simulations analysis Rayleigh's mathematical...

This study investigates the dynamic response of seabed pore pressure under wave loading, focusing on silty and layered conditions, with aim providing insights into stability coastal engineering design. A series flume experiments were conducted to explore spatial temporal evolution varying parameters, soil permeability degrees sediment stratification. The signals analyzed using Daubechies wavelets distinguish between oscillatory cumulative components in homogeneous seabeds. For seabeds, two...

The Cassini missions have identified the tiger stripes on Enceladus as source of both thermal emission and plume jets. hot spots in are highly localized, plumes suggest active hydrothermal processes within subglacial ocean Enceladus. However, understanding mechanism responsible for heat anomalies remains a challenge. About 60 y ago, geoscientist George Veronis proposed model cold water oceans, along with classical notion 1/3 scaling relationship between vertical transfer Rayleigh number ( Ra...

Purpose: CD3-based Bispecific T-cell engagers (BiTEs) are effective for solid tumors due to their tumor specificity and tissue penetration, but they face challenges like short half-lives narrow therapeutic windows. Innovative delivery systems, thermosensitive hydrogels, show the potential enhance stability, sustained release, efficacy. Methods: We developed PEGylated PLGA (PEG–PLGA) hydrogels with a nonshrinkable property (nsTPPgels) controlled release loaded them bispecific anti-prostate...

An alternative computational procedure for numerically solving a class of variational problems arising from rigorous upper-bound analysis forced-dissipative infinite-dimensional nonlinear dynamical systems, including the Navier-Stokes and Oberbeck-Boussinesq equations, is analyzed applied to Rayleigh-Bénard convection. A proof that only steady state which this numerical algorithm can converge required global optimal relevant problem given three canonical flow configurations. In contrast with...

High-Rayleigh-number ( $Ra$ ) convection in an inclined two-dimensional porous layer is investigated using direct numerical simulations (DNS) and stability variational upper-bound analyses. When the inclination angle $\unicode[STIX]{x1D719}$ of satisfies $0^{\circ }<\unicode[STIX]{x1D719}\lesssim 25^{\circ }$ , DNS confirm that flow exhibits a three-region wall-normal asymptotic structure accord with strictly horizontal $\unicode[STIX]{x1D719}=0^{\circ case, except as increased time-mean...

Motivated by the persistence of natural carbon dioxide ( $\text{CO}_{2}$ ) fields, we investigate convective dissolution at low pressure (below 1 MPa) in a closed system, where gas declines as convection proceeds. This introduces negative feedback that reduces rate even before brine becomes saturated. We analyse case an ideal with solubility given Henry’s law, limits very and high Rayleigh numbers. The equilibrium state this system is determined dimensionless capacity,...

A novel online control strategy using neuro-fuzzy theory for gust-response alleviation is described, and a gust-response-alleviation online-adjusted system designed based on this approach. Unlike the traditional adaptive systems, system, which consists of one host can appropriately adjust parameters each controller according to different real models flight situations. The simulations show that robust. For types gusts structures with errors even time delay, always provide stable...

We investigate the flow structure and dynamics of moderate-Rayleigh-number ( R a ) thermal convection in two-dimensional inclined porous layer. High-resolution numerical simulations confirm emergence O 1 aspect-ratio large-scale convective rolls, with one ‘natural’ roll rotating counterclockwise direction ‘antinatural’ clockwise direction. As inclination angle ϕ is increased, background mean shear intensifies natural-roll motion, while suppressing antinatural-roll motion. Our also reveal—for...

Motivated by geological carbon dioxide (CO$_2$) storage, many recent studies have investigated the fluid dynamics of solutal convection in porous media. Here we study convective dissolution CO$_2$ a closed system, where pressure gas declines as proceeds. This introduces negative feedback that reduces rate even before brine becomes saturated. We analyse case an ideal with solubility given Henry's law, limits very low and high Rayleigh numbers. The equilibrium state this system is determined...

Recent direct numerical simulations (DNS) and computations of exact steady solutions suggest that the heat transport in Rayleigh-Bénard convection (RBC) exhibits classical [Formula: see text] scaling as Rayleigh number with Prandtl unity, consistent Malkus-Howard's marginally stable boundary layer theory. Here, we construct conditional upper lower bounds for two-dimensional RBC subject to a physically motivated marginal linear-stability constraint. The estimate is derived using...

Improved upper bounds on viscous energy dissipation rates of wall-driven shear flow subject to uniform injection and suction are computationally determined. The so-called “background” variational formulation is implemented via a time-stepping numerical scheme determine optimal estimates. Shear Reynolds numbers range from 50 40 000 with angles up 2°. computed for preselected at high significantly improve the rigorously estimated ones. Our results suggest that steady laminar nonlinearly stable...

We study the fractionation of two components between a well-mixed gas and saturated convecting porous layer. Motivated by geological carbon dioxide (CO$_2$) storage we assume that convection is driven only dissolved concentration first component, while second acts as tracer with increased diffusivity. Direct numerical simulations for at high Rayleigh numbers reveal partitioning components, in general, does not follow trend, commonly assumed. Initially, increases diffusivity also increase its...