Search results for "Flow velocity"

Normalwerterstellung von Blutströmungsgeschwindigkeiten an der Arteria mesenterica superior bei Früh- und Reifgeborenen mit der Duplexsonographie

1994

In a prospective study blood flow velocity measurements were performed in 110 "healthy" newborn with duplex Doppler sonography in the superior mesenteric artery to obtain standard values. In 49 of these neonates 15, 30, and 45 minutes following feeding examinations were performed. Peak systolic flow velocity, end systolic flow velocity, time average flow velocity and time average maximum flow velocity were determined, the resistance and Pourcelot index as well as the volume blood flow were calculated. The children's gestational age was 27-42 weeks, the postnatal age was 2-68 days and the body weight was 920-4190 g. All measured blood flow velocities showed a synchronous relation to feeding …

Duplexsonographie abdomineller Gefäße

1987

Duplex sonography is a non-invasive procedure which permits the determination of flow velocity and direction in visceral vessels. Results in 50 normals have shown that small arteries can be evaluated in about 50% of cases. The portal venous system can be demonstrated in all cases; average flow velocity and volume is 15.2 +/- 2.8 cm/s and 694 +/- 230 ml/min, corresponding with the values obtained by invasive methods. Clinical application for duplex examinations can be found in portal hypertension, varices, thromboses, aneurysms and transplant kidneys.

River flow monitoring: LS-PIV technique, an image-based method to assess discharge

2022

The measurement of the river discharge within a natural ort artificial channel is still one of the most challenging tasks for hydrologists and the scientific community. Although discharge is a physical quantity that theoretically can be measured with very high accuracy, since the volume of water flows in a well-defined domain, there are numerous critical issues in obtaining a reliable value. Discharge cannot be measured directly, so its value is obtained by coupling a measurement of a quantity related to the volume of flowing water and the area of a channel cross-section. Direct measurements of current velocity are made, traditionally with instruments such as current meters. Although measur…

Entropic model application to identify cross-sectional flow effect on velocity distribution in a large amplitude meandering channel

2020

Abstract Literature shows the application of the entropy concept in open channels flow. No existing research has been addressed to the application of the entropy concept for evaluating the effect of secondary flow which especially develops in curved channels. The purpose of this paper is to explore the possibility to evaluate the effect of the secondary flow on the stream-wise velocity distribution starting only from the knowledge of the surface velocity and the entropic concept application. The analysis is conducted with the aid of data collected in a large-amplitude meandering laboratory flume for two different values of the width-to-depth ratio. Results show that the location of the maxi…

Experimental investigation on turbulent structures and sediment transport

2011

Role of vegetation on flow hydrodynamics and erosion processes

2011

ANALYSIS OF VELOCITY FIELD AND TURBULENCE CHARACTERISTICS OF FLOW IN A VEGETATED LABORATORY FLUME

2011

Vegetation altering hydrodynamic conditions of an open channel flow controls the exchanges of sediment, nutrients and contaminants. Thus, the knowledge of the hydraulic characteristics of flow over vegetation is very important to support the management of fluvial processes. But, the analysis of the hydrodynamic conditions is complex because vegetation is flexible in varying degrees and it oscillates in the flow changing position. Furthermore, because of temporal changing of roughness due to natural vegetative growth, the response of vegetation to the flow can change in time. Many theoretical and experimental investigations have been performed in order to analyze both the mean flow and turbu…