Two-Dimensional Simulation Model of Sediment Removal and Flow in Rectangular Sedimentation Basin

A steady, two-dimensional numerical model was created to study the hydrodynamics of a rectangular sedimentation basin under turbulent conditions. The strip integral method was used to formulate the flow equations, using a forward marching scheme for solving the governing partial differential equations of continuity, momentum, advection–diffusion, turbulent kinetic energy, and its dissipation. In this way the flow equations were converted to a set of ordinary differential equations (ODEs) in terms of the key physical parameters. These parameters, along with a set of shape functions, describe flow variables including the velocity, the concentration of suspended sediments, and both the kinetic energy and its dissipation rate. Four Gaussian distributions were investigated, one corresponding to each flow parameter. In order to calculate the turbulent shear stresses, a two-equation turbulence model (i.e., k-ε model) was used. A fourth order Runge–Kutta method numerically integrates the set of ODEs. Simulation results were compared with experimental data, and close agreement (generally within 5–10%) was observed.     

The context of aggressive behavior in marriage: A longitudinal study of newlyweds.

Under what circumstances are spouses more or less likely to engage in aggressive behaviors? To address this question, the current study drew on multiple longitudinal assessments of 1st-married newlyweds to examine correlates of within-subject variability in aggressive behavior. Controlling for marital satisfaction, the authors found that spouses were more likely to engage in physical aggression at times when they engaged in higher levels of psychological aggression. Additionally, husbands reporting higher levels of chronic stress were more likely to engage in physical aggression overall and were more likely to engage in physical aggression when they were experiencing higher than average levels of acute stress. These results highlight how demands and supports in the context external to a marriage may affect processes within the marriage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

To Know You Is to Love You: The Implications of Global Adoration and Specific Accuracy for Marital Relationships.

Despite the strong positive feelings that characterize newlyweds, many marriages end in disappointment. To understand this shift, the authors argue that although newlyweds' global relationship evaluations may be uniformly positive, not all spouses base their global adoration on an accurate perception of their partner's specific qualities. Two longitudinal studies confirmed that whereas most newlyweds enhanced their partners at the level of their global perceptions, spouses varied significantly in their perceptions of their partners' specific qualities. For wives, but not for husbands, more accurate specific perceptions were associated with their supportive behaviors, feelings of control in the marriage, and whether or not the marriage ended in divorce. Thus, love grounded in specific accuracy appears to be stronger than love absent accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How do constraints on leaving a marriage affect behavior within the marriage?

Like relationship satisfaction, constraints on leaving a relationship have been described as a component of global commitment. But do constraints increase or decrease efforts to maintain the relationship? To address this question, the authors of the current article describe 3 independent studies of spouses and married couples. Across all studies, wives who perceived more constraints on leaving the marriage exhibited lower levels of negative behavior only when their husbands were relatively unconstrained. In Study 3, this association was especially pronounced among less satisfied wives. In Study 2, spouses' perceived constraint also interacted to predict husbands' behavior, but in the opposite direction: Husbands who perceived more constraints behaved less negatively when their wives were similarly constrained but more negatively when their wives were less constrained. These results highlight differences in behavior between couples who persist in marriage because they desire to and those who endure because they have to, raising questions about measures of global commitment that obscure these distinctions. They also highlight the need for a dyadic perspective on the forces that keep relationships together. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Numerical modeling of the effects of roughness on flow and eddy formation in fractures

The effect of roughness on flow in fractures was investigated using lattice Boltzmann method (LBM). Simulations were conducted for both statistically generated hypothetical fractures and a natural dolomite fracture. The effect of increasing roughness on effective hydraulic aperture, Izbash and Forchheimer parameters with increasing Reynolds number (Re) ranging from 0.01 to 500 was examined. The growth of complex flow features, such as eddies arising near the fracture surface, was directly associated with changes in surface roughness. Rapid eddy growth above Re values of 1, followed by less rapid growth at higher Re values, suggested a three-zone nonlinear model for flow in rough fractures. This three-zone model, relating effective hydraulic conductivity to Re, was also found to be appropriate for the simulation of water flow in the natural dolomite fracture. Increasing fracture roughness led to greater eddy volumes and lower effective hydraulic conductivities for the same Re values.     

Systematic Surge Protection for Worst-Case Transient Loadings in Water Distribution Systems

Estimating appropriate water demands for the design of a distribution system is itself difficult, but the continuously fluctuating nature of these demands has the added potential of creating water hammer problems that might result in catastrophic pipeline or system failure. To first identify and then avoid these eventualities, this paper searches a predefined set of possible water hammer events in water distribution systems to identify the most severe transient loadings and then conducts a search for suitable surge protection strategies. Genetic algorithms and particle swarm optimization are combined with transient analysis first to identify a set of worst-case loads and then to seek an optimal protection strategy to cope with them. Case studies show that the worst case is not always obvious and cannot always be assumed a priori to correspond with high or low demand scenarios. Both the search for the worst-case loading and its associated optimal protection strategies are strongly sensitive to the characteristics of both the pipe system and the candidate transient events.     

Numerical modelling of flow and transport in rough fractures

Simulation of flow and transport through rough walled rock fractures is investigated using the latticeBoltzmann method （LBM） and random walk （RW）, respectively. The numerical implementation isdeveloped and validated on general purpose graphic processing units （GPGPUs）. Both the LBM and RWmethod are well suited to parallel implementation on GPGPUs because they require only next-neighbourcommunication and thus can reduce expenses. The LBM model is an order of magnitude faster onGPGPUs than published results for LBM simulations run on modern CPUs. The fluid model is verified forparallel plate flow, backward facing step and single fracture flow; and the RWmodel is verified for pointsourcediffusion, Taylor-Aris dispersion and breakthrough behaviour in a single fracture. Both algorithmsplace limitations on the discrete displacement of fluid or particle transport per time step to minimise thenumerical error that must be considered during implementation.
2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.     

Valve Closure in Graph-Theoretical Models for Slow Transient Network Analysis

A valve closure algorithm is presented for inclusion within a slow transient (rigid water column) pipe network model. The algorithm is specifically formulated for (but not limited to) node-based, graph-theoretical models and is both direct and accurate. It is distinguished from conventional approaches by its direct assignment of the final discharge at closure to zero and subsequent use of the head loss at the closing valve to compute the flow rate in pipes incident to the closing valve. As a result, redistribution of residual flow prior to closure to these incident pipes is not required, leading to a less computationally demanding and more robust algorithm than previously published valve closure procedures. Application of the valve closure algorithm is illustrated in a pipe network, which also nicely demonstrates again the relation between rigid water column and water hammer models.