scholarly journals Flow Characteristics through Saturated Soil: Experimental Study

2020 ◽  
Vol 16 ◽  
Keyword(s):  
Critical Analysis ◽  
Soft Soil ◽  
Flow Characteristics ◽  
Saturated Soil ◽  
Nonlinear Flow ◽  
Critical Flow ◽  
Test Results ◽  
Critical Flow Velocity ◽  
Linear And Nonlinear ◽  
Fluid Characteristics

The flow characteristics through saturated soil is complex. For low heads, the flow is essentially linear, where Darcy’s law is applicable. For higher head, the flow is nonlinear and mathematically identified as Forchheimer’s flow. The critical flow velocity for this transition and the relevant Reynold’s number depends upon several factors, including soil and fluid characteristics. In this paper, an experimental investigation has been carried out by means of falling head permeameter with locally available soft soil sample. A critical analysis and interpretations of the test results to identify the linear and nonlinear flow characteristics have been performed and important conclusions are drawn therefrom.

Fluidelastic Tube Vibration in a Heat Exchanger Designed for Sodium-to-Air Operation

1975 ◽  
Vol 97 (4) ◽  
pp. 561-568 ◽  
Author(s):  
H. Halle ◽  
B. L. Boers ◽  
M. W. Wambsganss
Keyword(s):  
Heat Exchanger ◽  
Flow Velocity ◽  
Test Facility ◽  
Critical Flow ◽  
Test Results ◽  
Critical Flow Velocity ◽  
Flow Induced Vibrations ◽  
Temperature Test ◽  
Dependent Mechanism

Analysis and testing were performed to evaluate the potential for flow induced vibrations of the finned U-tubes of a sodium-to-air dump heat exchanger of the Fast Flux Test Facility (FFTF). The analysis showed that fluidelastic vibration of the U-bend sections, caused by a displacement-dependent mechanism, could be experienced. Consequently, model tests, with prototypic tubing and stagnant water simulating the sodium mass on the tubeside, were performed. The tests consisted of subjecting the overhanging U-bends of a bank of five U-tubes to a range of air flow velocities at room temperature. Test results showed that, for a given support and restraint condition, a critical flow velocity exists above which large vibration amplitudes are induced. Characterization of the critical flow velocity was investigated. Supplementary single tube experiments determined vortex shedding frequencies, U-tube natural frequencies, damping, and, separately, the effect of internal water flow.

scholarly journals Hybrid Scour Depth Prediction Equations for Reliable Design of Bridge Piers

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2019
Author(s):  
Hossein Hamidifar ◽  
Faezeh Zanganeh-Inaloo ◽  
Iacopo Carnacina
Keyword(s):  
Flow Velocity ◽  
Critical Velocity ◽  
Depth Estimation ◽  
Hybrid Models ◽  
Velocity Estimation ◽  
Bridge Piers ◽  
Critical Flow ◽  
Scour Depth ◽  
Critical Flow Velocity ◽  
Estimation Equations

Numerous models have been proposed in the past to predict the maximum scour depth around bridge piers. These studies have all focused on the different parameters that could affect the maximum scour depth and the model accuracy. One of the main parameters individuated is the critical velocity of the approaching flow. The present study aimed at investigating the effect of different equations to determine the critical flow velocity on the accuracy of models for estimating the maximum scour depth around bridge piers. Here, 10 scour depth estimation equations, which include the critical flow velocity as one of the influencing parameters, and 8 critical velocity estimation equations were examined, for a total combination of 80 hybrid models. In addition, a sensitivity analysis of the selected scour depth equations to the critical velocity was investigated. The results of the selected models were compared with experimental data, and the best hybrid models were identified using statistical indicators. The accuracy of the best models, including YJAF-VRAD, YJAF-VARN, and YJAI-VRAD models, was also evaluated using field data available in the literature. Finally, correction factors were implied to the selected models to increase their accuracy in predicting the maximum scour depth.

scholarly journals Experimental Study on Improvement of Marine Soft Soil with Alkali Residue

2018 ◽  
Vol 53 ◽  
pp. 04021
Author(s):  
SHAO Yong ◽  
LIU Xiao-li ◽  
ZHU Jin-jun
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Void Ratio ◽  
Soft Soil ◽  
Compressive Modulus ◽  
Engineering Properties ◽  
Test Results ◽  
Use Of Resources ◽  
One Year

Industrial alkali slag is the discharge waste in the process of alkali production. About one million tons of alkali slag is discharged in China in one year. It is a burden on the environment, whether it is directly stacked or discharged into the sea. If we can realize the use of resources, it is a multi-pronged move, so alkali slag is used to improve solidified marine soft soil in this paper. The test results show that the alkali residue can effectively improve the engineering properties of marine soft soil. Among them, the unconfined compressive strength and compressive modulus are increased by about 10 times, and the void ratio and plasticity index can all reach the level of general clay. It shows that alkali slag has the potential to improve marine soft soil and can be popularized in engineering.

An Analysis of In-Flow Fluidelastic Instability Based on a Physical Insight

2014 ◽  
Author(s):  
Tomomichi Nakamura
Keyword(s):  
Flow Velocity ◽  
Flow Instability ◽  
Pressure Sensors ◽  
Measured Data ◽  
Critical Flow ◽  
Nonlinear Phenomenon ◽  
Critical Flow Velocity ◽  
Fluid Force ◽  
Tube Arrays ◽  
Fluidelastic Instability

Fluidelastic vibration of tube arrays caused by cross-flow has recently been highlighted by a practical event. There have been many studies on fluidelastic instability, but almost all works have been devoted to the tube-vibration in the transverse direction to the flow. For this reason, there are few data on the fluidelastic forces for the in-flow movement of the tubes, although the measured data on the stability boundary has gradually increased. The most popular method to estimate the fluidelastic force is to measure the force acting on tubes due to the flow, combined with the movement of the tubes. However, this method does not give the physical explanation of the root-cause of fluidelastic instability. In the work reported here, the in-flow instability is assumed to be a nonlinear phenomenon with a retarded or delayed action between adjacent tubes. The fluid force acting on tubes are estimated, based on the measured data in another paper for the fixed cylinders with distributed pressure sensors on the surface of the cylinders. The fluid force acting on the downstream-cylinder is assumed in this paper to have a delayed time basically based on the distance between the separation point of the upstream-cylinder to the re-attachment point, where the fluid flows with a certain flow velocity. Two models are considered: a two-cylinder and three–cylinder models, based on the same dimensions as our experimental data to check the critical flow velocity. Both models show the same order of the critical flow velocity and a similar trend for the effect of the pitch-to-diameter ratio of the tube arrays, which indicates this analysis has a potential to explain the in-flow instability if an adequate fluid force is used.

scholarly journals Experimental Investigation of Water-Sand Mixed Fluid Initiation and Migration in Filling Fracture Network during Water Inrush

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Bin Yang ◽  
Tianhong Yang
Keyword(s):  
Particle Size ◽  
Critical Velocity ◽  
Network Flow ◽  
Water Inrush ◽  
Functional Relation ◽  
Flow Characteristics ◽  
Fracture Network ◽  
Nonlinear Flow ◽  
Two Phase ◽  
And Migration

For water inrush induced by fracture network flow, the critical velocity of the incipient motion of sand particles was obtained, and the functional relation between critical velocity and particle size was established through a series of tests on the nonlinear flow characteristics of a filling fracture network. The influence of the particle size distribution, hydrodynamic force, and geometric features of the fracture network on the characteristics of particle loss; distribution laws; and water-sand, two-phase migration was also explored. Moreover, the interactions amongst water, movable particles, the surface of the skeleton, and fracture walls, and the formation mechanism of the flow channel were qualitatively analyzed. In addition, the change rules of the mass loss characteristics and porosity of the samples with time were tested successfully. The calculation methods of the permeability and non-Darcy factor of the filling fracture network were also determined.

scholarly journals Perbandingan Pengujian Konsolidasi Menggunakan Alat Rowe Cell dan Oedometer pada Tanah Lanau Lunak

2020 ◽  
Vol 22 (2) ◽  
pp. 149-155
Author(s):  
Iskandar ◽  
Rabiya
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soil Samples ◽  
Soil Parameters ◽  
Soil Consolidation ◽  
Test Results ◽  
Soft Soils ◽  
Better Than ◽  
Rowe Cell

Soil consolidation testing using an oedometer and rowe cell. Oedometers are often used on clay and soft soils. However, in the development of the rowe cell device, the results of lowering soft soil were better than the oedometer. The advantage of this rowe cell is that it can determine the saturation value of the soil samples tested. The rowe cell tester can measure the pore water pressure at the beginning and end of each consolidation stage. This rowe cell can provide suitable settlement for soft soils. This consolidation test to obtain soil parameters such as Cv and Cc by using the rowe cell tool. After that, from the test results, the two tools were compared.

scholarly journals Society 5.0: a Self-Devouring System

2019 ◽  
Vol 8 (2) ◽  
pp. 4001-4004 ◽  
Keyword(s):  
Development Strategy ◽  
Coming Out ◽  
Critical Analysis ◽  
Human Person ◽  
Development Program ◽  
Cultural Development ◽  
Global Problems ◽  
The Subject ◽  
Linear And Nonlinear ◽  
Principle Of Complementarity

The subject matter of the paper is a philosophical analysis of the civilization-cultural development strategy Society 5.0. The strategy emerged from the idea of the Japanese government formulated in 2016. A critical analysis shows that this development program contains systemic contradictions and risks. Nevertheless, the idea seems to be achieving the goals of modern humanism in the conditions of information civilization development. The research methodology stems from the principles of consistency, complementarity, fractality and the dialectics of the concepts which are as follows: culture and civilization, linear and nonlinear development, etc. There is much evidence that today the integration of mankind has become global. The process leads to, firstly, the changes in the scales of human subjectivity, and secondly, the attitude of man to chance and need. All these characteristics are fraught with threats to the holistic existence of mankind, and the possibility of people’s coming out of the crisis to the new levels of development. Private culture, which previously served as a powerful integrator of society, is losing the opportunity to carry out an ideological, and as a result, educational function in the conditions of an informational civilization. The transition of humanity from the monocultural to the multicultural way requires of relations between culture and civilization being based on the principles of complementarity. The construction of humanity as a self-organizing system is possible only through the management of civilization processes through culture, i.e., through the spiritual improvement of the human person. Evidence suggests that the principles laid down in the Society 5.0 development program do not meet these requirements. The program aims to implement the principle of positive feedback, as it tries to solve global problems of civilization with civilization practices. Theoretically, the achievement of harmonious relations between civilization and culture becomes possible on condition of the principle of complementarity. However, this principle also implies the rule of negative feedback

scholarly journals Experimental Research on Creep Characteristics of Nansha Soft Soil

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Qingzi Luo ◽  
Xiaoping Chen
Keyword(s):  
Pearl River Delta ◽  
Soft Soil ◽  
Creep Damage ◽  
Pearl River ◽  
Test Results ◽  
Creep Failure ◽  
Consolidation Pressure ◽  
Creep Characteristics ◽  
Triaxial Creep ◽  
Shear Box

A series of tests were performed to investigate the creep characteristics of soil in interactive marine and terrestrial deposit of Pearl River Delta. The secondary consolidation test results show that the influence of consolidation pressure on coefficient of secondary consolidation is conditional, which is decided by the consolidation state. The ratio of coefficient of secondary consolidation and coefficient of compressibilityCa/Ccis almost a constant, and the value is 0.03. In the shear-box test, the direct sheer creep failure of soil is mainly controlled by shear stress rather than the accumulation of shear strain. The triaxial creep features are closely associated with the drainage conditions, and consolidation can weaken the effect of creep. When the soft soil has triaxial creep damage, the strain rate will increase sharply.

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