Graphically interpreting how incision thresholds influence topographic and scaling properties of modeled landscapes

We examine the influence of incision thresholds on topographic and scaling properties of landscapes that follow a landscape evolution model (LEM) with terms for stream-power incision, linear diffusion, and uniform uplift. Our analysis uses three main tools. First, we examine the graphical behavior of theoretical relationships between curvature and the steepness index (which depends on drainage area and slope). These relationships plot as straight lines for the case of steady-state landscapes that follow the LEM. These lines have slopes and intercepts that provide estimates of landscape characteristic scales. Such lines can be viewed as counterparts of slope–area relationships, which follow power laws in detachment-limited landscapes but not in landscapes with diffusion. We illustrate the response of these curvature–steepness index lines to changes in the values of parameters. Second, we define a Péclet number that quantifies the competition between incision and diffusion, while taking the incision threshold into account. We examine how this Péclet number captures the influence of the incision threshold on the degree of landscape dissection. Third, we characterize the influence of the incision threshold using a ratio between it and the steepness index. This ratio is a dimensionless number in the case of the LEM that we use and reflects the fraction by which the incision rate is reduced due to the incision threshold; in this way, it quantifies the relative influence of the incision threshold across a landscape. These three tools can be used together to graphically illustrate how topography and process competition respond to incision thresholds.

A Modeling Framework of Electrochemo-Mechanics of Lithium-Ion Battery: Part I. Impedance Response of Single Particle

An impedance model considering the electrochemo-mechanics of a single particle in lithium-ion batteries is proposed in the work. In this model, the interaction between the Li+ diffusion and the surface reaction and mechanics is considered. The characteristic semicircle in low frequency range, which is due to the stress effect, is found. The visualizability of the stress-induced semicircle in the experiments is found to be related to the characteristic frequency of the Li+ diffusion. Through simplifying the model expression under three different limiting cases, two dimensionless number α=-θRT/F/∂U/(∂c_s ) and β=1+θc ̅_s are defined to evaluate the stress effect. The proposed mechanic-modified model is verified through the results of thin-film electrode considering the difficulty in performing single particle experiments for nano-sized particle and similarity of the single particle and thin film electrode. This work can be supplemented with the theory of porous electrode to analyze the impedance response of a porous electrode, which will be discussed in the next part of this series of papers.

A NEW SCALING STRATEGY OF BUBBLING FLUIDIZED BED REACTORS BASED ON POPULATION-BALANCE MODEL

This work proposes a new strategy for the scaling of bubbling fluidized bed reactors. This strategy is based on the bubble size distribution, bubble coalescence phenomenon, and the chemical reactivity, allowing to deduct the dimensionless number Chejne-Macias-Maya that must remain constant at different scales to guarantee the fluidization regime. The proposed strategy is validated from computational simulations carried out at different operating conditions. Additionally, limits for the validity of this scaling strategy were determined, which agrees with those reported in the literature.

A Study on the Customized Design Criteria of Pedestrians’ Specifications Using a Dimensionless Number

Worldwide, the population is aging at a gradually increasing speed, due to a decrease in the population and the development of medical facilities and technology. Due to the rapid aging of the population, social infrastructure will also need to be transformed into convenient facilities for the elderly. Walking facilities have been manufactured based on body size measured for general adults. Accordingly, it is necessary to prepare a new design standard suitable for the characteristics of the elderly. It is very difficult to establish standardized values for the elderly because there is a large difference in gait characteristics as well as body size. Therefore, in this study, gait characteristics were measured for the elderly with the standard physique of the elderly in Korea, and the measured gait characteristic variable values were converted into dimensionless numbers to calculate coefficients with more representativeness. The calculated coefficient is expected to be more universally applied and utilized because factors that may affect it depending on the size of the body are removed. When designing a walking facility, the average body size is applied to convert it back into necessary walking attribute information (including units), and this is presented as an example from Korea. It is expected that the presented results can be used to design more suitable and safe pedestrian facilities for an aging society.

Dimensional Analysis of Compound Section in The Regulate Section Channel Model for Maintenance Main Channel

A dimensionless number is used to express the relationship between parameters and is used to describe the research results. Commonly used dimensional analysis methods are the Basic Echelon method, the Buckingham method, the Rayleight method, the Stepwise method and the Langhaar method. The compound section in the regulated section channel model aims to make the section convenient to the flow existing discharge at tidal conditions, in sediment flushing. In this study using the Buckingham’s method of dimensional analysis to determine the weight equation for the flushing sediment (w) and the variables that have been scaled on the flume, W = • (B, B*, h, h*, ⊗h, t, V, Q, g, W,)w,)S), where B is the width of the river (cm), B* is the width of the Flushing section (cm), h is the height of the water level (cm), h* is the height of the flushing section (cm), ®h is the difference in water level (cm), t is the tidal time period (s), V is the flow velocity (cm/s), Q is the water discharge (cm3/s), g is the gravity (cm/s2), )S is the mass density of the sediment (gr/cm3), )w is the density of the water mass (gr/cm3). From the analysis results obtained equations = B * B . h * h . Δ h h . v g t . Q g h 2 t . ρ s h 3 . Where w is the weight of the flushing sediment (gr), B * B is the ratio of the design cross-sectional width to the width of the estuary, h * h is the ratio of the flushing cross-sectional height to the water level, Δ h h is the ratio of the height water level to water depth, v g t is the velocity of falling sediment, Q g h 2 t is the discharge of sediment flushing, ρ s h 3 is the hydrostatic pressure.

Numerical Study on the Influence of Vortex Generator Arrangement on Heat Transfer Enhancement of Oil-Cooled Motor

At present, vortex generators have been extensively used in radiators to improve the overall heat transfer performance. However, there is no research on the effect of vortex generators on the ends of motor coils. Meanwhile, the current research mainly concentrates on the attack angle, shape and size, and lacks a detailed study on the transverse and longitudinal distance and arrangement of vortex generators. In this paper, the improved dimensionless number is used as the key index to evaluate the overall performance of enhanced heat transfer. Firstly, the influence of the attack angle on heat transfer enhancement is discussed through a single pair of rectangular vortex generators, and the results demonstrate that the vortex generator with a 45° attack angle is superior. On this basis, we compare the effects of different longitudinal distances (2 h, 4 h, and 6 h, h meaning the height of vortex generator) on enhanced heat transfer under four distribution modes: Flow-Up (FU), Flow-Down (FU), Flow-Up-Down (FUD), Flow-Down-UP (FDU). Thereafter, the performances of different transverse distances (0.25 h, 0.5 h, and 0.75 h) of the vortex generators are numerically simulated. When comparing the longitudinal distances, FD with a longitudinal distance of 4 h (FD-4h) performs well when the Reynolds number is less than 4000, and FU with a longitudinal distance of 4 h (FU-4h) performs better when the Reynolds number is greater than 4000. Similarly, in the comparison of transverse distances, FD-4h still performs well when the Reynolds number is less than 4000, and FU with a longitudinal distance of 4 h and transverse distance of 0.5 h (FU-4h − 0.5h) is more prominent when the Reynolds number is greater than 4000.

Numerical simulation of the electroosmotic flow of the Carreau-Yasuda model in the rectangular microchannel

Purpose In this paper aims to investigate the numerical simulation of the electroosmotic flow of the Carreau-Yasuda model in the rectangular microchannel. Electromagnetic current is generated by applying an effective electric field in the direction of the current. Design/methodology/approach The non-Newtonian model used is the five-constant Carreau-Yasuda model which the non-Newtonian properties of the fluid can be well modeled. Using the finite difference method, the potential values at all points in the domain are obtained. Then, the governing equations (momentum conservation) and the energy equation are segregated and solved using a finite difference method. Findings In this paper, the effect of various parameters such as Weisenberg number, electrokinetic diameter, exponential power number on the velocity field and Brinkman and Pecklet dimensionless numbers on temperature distribution are investigated. The results show that increasing the Weissenberg dimensionless number and exponential power and diameter parameters reduces the maximum velocity field in the microchannel. Originality/value To the best of the authors’ knowledge, this study is reported for the first time.

Sorting of Poly-disperse Particle by Entrapment using Liquid Carrier System

A thin viscous layer is found over a substrate when it is immersed in a polymer solution. The layer thickness depends on the polymer and solvent type, their volume fraction, and the substrate. If the liquid solution contains particles, they are entrapped on the viscous polymer layer, acting as the binder. The trade-off between the viscous force and the centrifugal force on the particle determines the entrapment. Furthermore, the size of entrained particles are dictated by the binder concentration of the solution., A particle filtration technique is presented using the entrapment phenomenon from a poly-disperse mixture. A dimensionless number called the entrapment factor is introduced to correlate the particle entrapment with various parameters. By changing the entrapment factor, three distinct entrapment regimes are achieved and explained from a poly-disperse mixture. The experimental result shows that entrapped particles become larger as the factor increases, which can be controlled with multiple parameters of the dipping process. The proposed technique can lead to a filtration process of the wide-range poly-disperse particle mixture over the capillary filtration processes.

Experimental and Modeling Studies on Pressure Gradient Prediction for Horizontal Gas Wells Based on Dimensionless Number Analysis

Accurate prediction of pressure gradient in gas wells is the theoretical basis of gas well performance analysis, production optimization and deliquification technologies design. Experiment is the best access to characterize the flow behavior of gas wells. For low-pressure experimental investigation and gas wells, the most difference is the pressure (gas density), which could lead to totally different flow behavior. Dimensionless numbers are often used in the flow pattern maps to account for the flow similarities at different conditions, which means liquid holdup in the high pressure can be also predicted at low pressure conditions if we choose proper dimensionless numbers for pressure scaling up. However, no studies have focused on this point before. Besides, gas wells have high GLR, most empirical models were intended to developed for oil wells, which have greater weight in low GLR, decreasing the accuracy in gas wells. In order to predict the pressure gradient in horizontal gas wells, an experimental investigation of gas-water flow has been conducted. The experimental test matrix was designed to cover all the flow patterns. The experiment was conducted in a 5-m long pipe. The liquid holdup and pressure gradient were measured. Subsequently, the effect of gas velocity, liquid velocity, pipe diameter, and inclined angle on liquid holdup was analyzed. Then the dimensionless numbers proposed in the literature have been investigated and analyzed for pressure scaling up. Finally, a comprehensive model was established, which is developed for prediction pressure drop in gas wells. Some field and experimental data were provided to evaluate the new model. The results show that the Duns-Ros dimensionless number was not proper for pressure scaling up while the Hewitt-Robert Number performs best. Compared to widely used pressure gradient models with field data, the new model with Hewitt-Robert Number performed best, which shows that it is capable of dealing with prediction of pressure gradient in gas wells.