Generic Speed–Flow Models for Basic Freeway Segments on General-Purpose and Managed Lanes in Undersaturated Flow Conditions

2015 ◽  
Vol 2483 (1) ◽  
pp. 102-110 ◽  
Author(s):  
Seyedbehzad Aghdashi ◽  
Nagui M. Rouphail ◽  
Ali Hajbabaie ◽  
Bastian J. Schroeder
Keyword(s):  
General Purpose ◽  
Managed Lanes ◽  
Flow Conditions ◽  
Flow Models ◽  
Speed Flow

Study of the Response of PW Traffic Flow Model to a Bottleneck on a Circular Road and its Suitability for Heterogeneous Traffic Conditions

2021 ◽  
Vol 9 (4) ◽  
pp. 460-463
Keyword(s):  
Fluid Flow ◽  
Traffic Flow ◽  
Flow Model ◽  
Equation Model ◽  
Heterogeneous Traffic ◽  
Flow Conditions ◽  
Flow Models ◽  
Traffic Conditions ◽  
Model Response ◽  
Traffic Flow Models

The traffic flow conditions in developing countries are predominantly heterogeneous. The early developed traffic flow models have been derived from fluid flow to capture the behavior of the traffic. The very first two-equation model derived from fluid flow is known as the Payne-Whitham or PW Model. Along with the traffic flow, this model also captures the traffic acceleration. However, the PW model adopts a constant driver behavior which cannot be ignored, especially in the situation of heterogeneous traffic.This research focuses on testing the PW model and its suitability for heterogeneous traffic conditions by observing the model response to a bottleneck on a circular road. The PW model is mathematically approximated using the Roe Decomposition and then the performance of the model is observed using simulations.

Safety Impact of Weaving Distance on Freeway Facilities with Managed Lanes using Both Microscopic Traffic and Driving Simulations

2018 ◽  
Vol 2672 (39) ◽  
pp. 130-141 ◽  
Author(s):  
Qing Cai ◽  
Moatz Saad ◽  
Mohamed Abdel-Aty ◽  
Jinghui Yuan ◽  
Jaeyoung Lee
Keyword(s):  
Traffic Safety ◽  
Traffic Congestion ◽  
Driving Simulator ◽  
Negative Impact ◽  
Control Strategies ◽  
General Purpose ◽  
Valuable Insight ◽  
Lane Change ◽  
Simulation Studies ◽  
Managed Lanes

With the challenges of increasing traffic congestion, the concept of managed lanes (MLs) has been gaining popularity recently as a means to effectively improve traffic mobility. MLs are usually designed to be left-lane concurrent with an at-grade access/exit. Such a design forms weaving segments since it requires vehicles to change multiple general purpose lanes (GPLs) to enter or exit the ML. The weaving segments could have a negative impact on traffic safety in the GPLs. This study provides a comprehensive investigation of the safety impact of different lengths for each lane change maneuver on GPL weaving segments close to the ingress and egress of MLs through two simulation approaches: VISSIM microsimulation and driving simulator. The two simulation studies are developed based on traffic data collected from freeway I-95 in Miami, Florida. The results from the two simulation studies support each other. Based on the two simulation studies, it is recommended that 1,000 feet be used as the optimal length for per lane change at the GPLs weaving segments with MLs. The safety impact of traffic volume, variable speed limit control strategies, and drivers’ gender and age characteristics are also explored. This study can provide valuable insight for evaluating the traffic performance of freeway weaving segments with the presence of concurrent GPLs and MLs in a highway safety context. It also provides guidelines for future conversion of freeways to include MLs.

High Speed Flow through Perforated Plates

1960 ◽  
Vol 64 (590) ◽  
pp. 103-105
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Perforated Plate ◽  
Wire Mesh ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Perforated Plates ◽  
Speed Flow ◽  
Flow Through ◽  
Points Of View

The flow through porous screens has been widely studied from both the theoretical and experimental points of view. The most widely used types of screen are the wire mesh and the perforated plate, and the majority of the literature has been concerned with the former. Several attempts have been made to correlate the parameters governing the flow through such screens, i.e. the pressure drop, the flow conditions and the geometry of the mesh.

High Speed Flow Through Wire Gauzes

1959 ◽  
Vol 63 (584) ◽  
pp. 474-475 ◽  
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
Pressure Loss ◽  
High Speed ◽  
Static Pressure ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Speed Flow ◽  
Wire Gauze ◽  
Flow Through

The Flow of Fluids through screens has been widely studied with particular importance being attached to the measurement of the pressure drop caused by a screen and its relation to the screen geometry and the flow conditions. The majority of the investigations have been carried out on wire gauze screens mounted in ducts with air passing through them, the static pressure being measured on either side of the gauze. Attempts have been made by Weighardt Annand and Grootenhuisto correlate the gauze geometry with the pressure drop and to enable the pressure loss over a given screen and with given flow conditions to be predicted.

Determination of head losses in a surge chamber: Robert Bourassa power plant case study

2007 ◽  
Vol 34 (9) ◽  
pp. 1038-1047 ◽  
Author(s):  
Musandji Fuamba ◽  
Gilles Brosseau ◽  
Éric Mainville
Keyword(s):  
Power Plant ◽  
Three Dimensional ◽  
Hydraulic Head ◽  
Transportation Systems ◽  
Flow Conditions ◽  
Flow Models ◽  
Head Losses ◽  
Water Transportation

Optimal management of power plant units is achieved when the global efficiency of the units and the minimization of the total hydraulic head losses through the water transportation systems can be combined. Evaluating these hydraulic head losses appears to be very difficult due to the complexity of the flow conditions through the hydraulic structures. A hydraulic energy based method to determine head losses in the surge chamber has been proposed in this paper, as well as a method to manage the opening of units which would optimize the production of electricity. This method was applied to a case study, and successful results have been obtained showing how the head loss varies in the surge chamber.Key words: hydraulic head losses, power plant unit, surge chamber, unit efficiency, three-dimensional flow conditions, turbulent flow models, computational fluid dynamics.

The Effects of Inlet Boundary Layer Condition and Periodically Incoming Wakes on Secondary Flow in a Low Pressure Turbine Cascade

2020 ◽  
Author(s):  
Tobias Schubert ◽  
Silvio Chemnitz ◽  
Reinhard Niehuis
Keyword(s):  
Boundary Layer ◽  
Secondary Flow ◽  
High Speed ◽  
Low Pressure ◽  
Experimental Investigations ◽  
Turbine Cascade ◽  
Flow Conditions ◽  
Low Pressure Turbine ◽  
Speed Flow ◽  
Unsteady Inflow

Abstract A particular turbine cascade design is presented with the goal of providing a basis for high quality investigations of endwall flow at high-speed flow conditions and unsteady inflow. The key feature of the design is an integrated two-part flat plate serving as a cascade endwall at part-span, which enables a variation of the inlet endwall boundary layer conditions. The new design is applied to the T106A low pressure turbine cascade for endwall flow investigations in the High-Speed Cascade Wind Tunnel of the Institute of Jet Propulsion at the Bundeswehr University Munich. Measurements are conducted at realistic flow conditions (M2th = 0.59, Re2th = 2·105) in three cases of different endwall boundary layer conditions with and without periodically incoming wakes. The endwall boundary layer is characterized by 1D-CTA measurements upstream of the blade passage. Secondary flow is evaluated by Five-hole-probe measurements in the turbine exit flow. A strong similarity is found between the time-averaged effects of unsteady inflow conditions and the effects of changing inlet endwall boundary layer conditions regarding the attenuation of secondary flow. Furthermore, the experimental investigations show, that all design goals for the improved T106A cascade are met.

scholarly journals Speed-flow Models for Freeways

2011 ◽  
Vol 16 ◽  
pp. 26-36 ◽  
Author(s):  
Werner Brilon ◽  
Jan Lohoff
Keyword(s):  
Flow Models ◽  
Speed Flow

scholarly journals Transit times from rainfall to baseflow in headwater catchments estimated using tritium: the Ovens River, Australia

2015 ◽  
Vol 19 (9) ◽  
pp. 3771-3785 ◽  
Author(s):  
I. Cartwright ◽  
U. Morgenstern
Keyword(s):  
Transit Time ◽  
Headwater Streams ◽  
Stream Water ◽  
Mean Transit Time ◽  
Significant Proportion ◽  
Low Flow ◽  
Flow Conditions ◽  
Headwater Catchments ◽  
Flow Models ◽  
Transit Times

Abstract. Headwater streams contribute a significant proportion of the total flow to many river systems, especially during summer low-flow periods. However, despite their importance, the time taken for water to travel through headwater catchments and into the streams (the transit time) is poorly understood. Here, 3H activities of stream water are used to define transit times of water contributing to streams from the upper reaches of the Ovens River in south-east Australia at varying flow conditions. 3H activities of the stream water varied from 1.63 to 2.45 TU, which are below the average 3H activity of modern local rainfall (2.85 to 2.99 TU). The highest 3H activities were recorded following higher winter flows and the lowest 3H activities were recorded at summer low-flow conditions. Variations of major ion concentrations and 3H activities with streamflow imply that different stores of water from within the catchment (e.g. from the soil or regolith) are mobilised during rainfall events rather than there being simple dilution of an older groundwater component by event water. Mean transit times calculated using an exponential-piston flow model range from 4 to 30 years and are higher at summer low-flow conditions. Mean transit times calculated using other flow models (e.g. exponential flow or dispersion) are similar. There are broad correlations between 3H activities and the percentage of rainfall exported from each catchment and between 3H activities and Na and Cl concentrations that allow first-order estimates of mean transit times in adjacent catchments or at different times in these catchments to be made. Water from the upper Ovens River has similar mean transit times to the headwater streams implying there is no significant input of old water from the alluvial gravels. The observation that the water contributing to the headwater streams in the Ovens catchment has a mean transit time of years to decades implies that these streams are buffered against rainfall variations on timescales of a few years. However, impacts of any changes to land use in these catchments may take years to decades to manifest themselves in changes to streamflow or water quality.

Sign in / Sign up

Export Citation Format

Share Document