Prismatic Open Channel Research Articles

BOUNDARY SHEAR STRESS DISTRIBUTIONS IN SMOOTH RETANGULAR OPEN CHANNEL FLOWS.

Keywords NANYANG TECHNOLOGICAL UNIVERSITY, SINGAPORE SHEAR, STRESS, DISTRIBUTION, BOUNDARIES, SMOOTH, RECTANGULAR, OPEN, CHANNELS, FLOW, METHODS, ANALYTICAL, FLUIDS, THREE DIMENSIONAL, PERIMETER, WETTED, STEADY, UNIFORM, ASPECT, RATIOS, MODELS, MATHEMATICAL, HYDRAULICS, HYDRODYNAMICS, RIVERS, THEORY, MECHANISMS, ENERGY, TRANSPORTATION, INFLUENCE, ROUGHNESS, DISSIPATION... Show All

An approach toward rational design of constructed wetlands for wastewater treatment

A simulation-based design approach is used to find the optimal size a wetland constructed for wastewater treatment. The simulation scheme synthesizes submodels describing variable wastewater loadings, atmospheric moisture fluxes, contaminant fate and transport, and effluent release and recycle rules. The wetland is modeled as a lined densely vegetated prismatic open channel that behaves as a non-ideal plug flow reactor (PFR) with first-order temperature-dependent kinetics. The hydrodynamic equation for gradually varied unsteady free surface flow is linked with the one-dimensional advection diffusion decay equation for a nonconservative nonsorbing substance. The coupled equations are solved using an implicit finite difference method. The flexibility of the simulation approach is illustrated with four hypothetical examples which compare treatment performances among alternate wetland configurations and operating strategies. Results show that ambient temperature and the effluent release and recycle rule are much more important than precipitation and evaporation in determining the size of the wetland required to meet permit limits.

An example of advanced electronic macro spreadsheet programming

The range of use of electronic spreadsheets to the solution of engineering problems is increasing with the advancements in spreadsheet software and computer hardware. The recent introduction of macro spreadsheets has added problem-solving capabilities of considerable power to spreadsheet applications. This paper illustrates the potential of these macros by presenting a macro spreadsheet solution to a difficult engineering problem: the transient surface wave profile for unsteady flow in a prismatic open channel as solved by the method of characteristics. Command macros, function macros, subroutine macros, formatting, interaction with the user, and data file usage are all involved in the program. The solution utilizes several separate, but interconnected, macro spreadsheets; this assists the user in debugging the program and in making future modifications. Key words: computers, spreadsheets, macro programming, open channel flow, method of characteristics.

Erratum for “Debris Flow on Prismatic Open Channel”

Erratum for “Debris Flow on Prismatic Open Channel”

Debris Flow on Prismatic Open Channel

Reviews on the yield strength and viscosity of the interstitial clay slurry in debris flow prove that ordinary debris flow may be modeled as a dilatant fluid in which the intergranular forces dominate. Theoretical velocity distributions in dilatant fluid compare well with the experimental results when the value of a numerical constant is appropriately selected. The longitudinal profile of the lobate snout is satisfactorily analyzed by applying the theory of one-dimensional translation wave on an open channel, where the resistance coefficient is a function of concentration, depth, and grain diameter. A remarkable segregation of particles, in which the larger ones move upwards, occurs in debris flow due to the effects of collisions of particles. The accumulation of boulders in the front part of debris flow is a result of the faster transportation of the larger particles in the upper layer of the flow than that of the smaller ones in the lower layer.