Application of Fluid Dynamics in Geotechnical Engineering

Effects of Noradrenaline, Isoproterenol and Acetylcholine on Ureteral Resistance

Pressurizer is one of the most important components in reactor coolant system of a nuclear power plant, which operates normally at pressure of 15.4 MPa and temperature of 345°C[1]. The main function of pressurizer is to regulate the pressure in the reactor coolant system by either cooling the steam or heating the saturated water in its upper zone. When the pressure in the reactor coolant system increases, it will distribute cold water to decrease its temperature and pressure through atomizing the reactor coolant with swirl spray nozzle in pressurizer. Swirl nozzle is the key part of pressurizer with swirl structure of full cone spray pattern, and the atomization performance include drop size, spray angle and distribution, also it is characterized by huge flow rate and low pressure drop, and its atomization performance decides the quality of pressure control of the reactor coolant system. To enhance the independent design level of both pressurizer and cooling system, it’s necessary to study the atomization performance of swirl nozzle for nuclear reactor pressurizer. Aimed at improving atomization performance of swirl spray nozzle, the structure design methodology of nuclear reactor pressurizer was studied systematically in three aspects including theory design, numerical simulation and test confirm in this thesis. Through designing the swirl nozzle structure according to similar design formula of spray nozzle in theory, especially studying the influence of different structures that mainly include internal swirl structure on internal flow field of swirl nozzles, the primary structure parameters of swirl nozzle were confirmed. Then, through numerical simulation of the internal flow field, flow rate and pressure drop, and swirl core structure of the swirl nozzle (by building physical model and mathematic model according to the spray nozzle structure), the atomization performance of the nozzle was analyzed. On this basis, the typical swirl nozzle was designed and tested, which included spray angle, flow rate as well as pressure drop tests, and spray drop tests, and the applicability of the computational fluid dynamics (CFD) method was verified when it was applied in swirl nozzle design. Finally, the design method of swirl nozzle with deep groove of swirl core for pressurizer was put forward. Through this studying of theoretical calculation, numerical simulating and test, the correlation between the structural parameters of swirl nozzle and atomization performance was achieved, meanwhile design, analysis and test methods of spray nozzle with low pressure drop and huge flow rate were established. It is helpful to realize the independent design of pressurizer’s swirl nozzle and even to put forward the design methodology of pressurizer’s swirl nozzle with our own characteristic.

Subchannel analysis of critical heat flux in radially Non-uniform heated rod assembly at low flow rate

Water cluster ion intensity and distribution is affected by source conditions in direct sample analysis (DSA) ionization. Parameters investigated in this paper include source nozzle diameter, gas flow rate, and source positions relative to the mass spectrometer inlet. Schlieren photography was used to image the gas flow profile exiting the nozzle. Smaller nozzle diameters and higher flow rates produced clusters of the type [H + (H(2)O)(n)](+) with greater n and higher intensity than larger nozzles and lower gas flow rates. At high gas flow rates, the gas flow profile widened compared with the original nozzle diameter. At lower flow rates, the amount of expansion was reduced, which suggests that lowering the flow rate may allow for improvements in sampling spatial resolution.

The renal safety of sevoflurane.

Computational Fluid Dynamic Modeling of Urethral Strictures

To analyze the association between low saliva flow rates and the use of psychoactive drugs among the elderly. A cross-sectional study was carried out with 267 elderly people from 60 to 74 years of age who lived in a borough of the city of Londrina, Paraná State, Brazil. Individuals with high functional dependence or restricted to bed were excluded. Saliva flow rate was the dependent variable with values under the first tercile being considered as low flow rates (less than 0.44 ml/min). The continuous use of psychoactive drugs (antidepressant, antiepileptic, sedative, antipsychotic, hypnotic or sedative-hypnotic drugs) was the independent variable. Multivariate analysis was performed taking into account gender, age and smoking status. The majority of the elderly were women (80.5%), with a mean age of 66.5 years. Use of psychoactive drugs was observed among 31 elderly (11.6%). Mean saliva flow rate was 0.76 ml/min, lower among users of psychoactive drugs (0.67 ml/min). In the multivariate analysis, use of psychoactive drugs was associated with low saliva flow rates (<0.44 ml/min), independent of gender, age or smoking. Results show that there is an association between use of psychoactive drugs and low saliva flow rates in this group of independent and non-institutionalized elderly. These conclusions stress the need of a rational use of these drugs, particularly among the elderly.

Development of a portable grain mass flow sensor test rig

The Sawada-Kotera equations illustrate the non-linear wave phenomena in shallow water, ion-acoustic waves in plasmas, fluid dynamics, etc. In this article, the two-mode Sawada-Kotera equation (tmSKE) occurring in fluid dynamics is considered which is important model equations for shallow water waves, the capillary waves, the waves of foam density, the electro-hydro-dynamical model. The improved F-expansion and generalized exp $(-\phi (\zeta))$ -expansion methods are utilized in this model and abundant of solitary wave solutions of different kinds such as bright and dark solitons, multi-peak soliton, breather type waves, periodic solutions, and other wave results are obtained. These achieved novel solitary and other wave results have significant applications in fluid dynamics, applied sciences and engineering. By granting appropriate values to parameters, the structures of few results are presented in which many structures are novel. The graphical moments of the results are provided to signify the impact of the parameters. To explain the novelty between the present results and the previously attained results, a comparative study has been carried out. The restricted conditions are also added on solutions to avoid singularities. Furthermore, the executed techniques can be employed for further studies to explain the realistic phenomena arising in fluid dynamics correlated with any physical and engineering problems.

Physics-based models have been mainstream in fluid dynamics for developing predictive models. In recent years, machine learning has offered a renaissance to the fluid community due to the rapid developments in data science, processing units, neural network based technologies, and sensor adaptations. So far in many applications in fluid dynamics, machine learning approaches have been mostly focused on a standard process that requires centralizing the training data on a designated machine or in a data center. In this article, we present a federated machine learning approach that enables localized clients to collaboratively learn an aggregated and shared predictive model while keeping all the training data on each edge device. We demonstrate the feasibility and prospects of such a decentralized learning approach with an effort to forge a deep learning surrogate model for reconstructing spatiotemporal fields. Our results indicate that federated machine learning might be a viable tool for designing highly accurate predictive decentralized digital twins relevant to fluid dynamics.

We present a 43-year old female patient, admitted to the intensive care unit, recovering from a Bentall procedure because of a supra-coronary aneurysm and unicuspid aortic valve. Few hours following surgery,a marked lactic acidosis, hypoxemia and increased central venous pressure developed. Pulmonary angio-CT was performed to exclude pulmonary embolism. Because of severe peripheral vasoconstriction, iodine contrast could only be administered through a narrow lumen central venous catheter, which limited the maximum flow rate to 1.5 ml/s. Images were performed with triggering in the pulmonary trunk. Review of the images showed no evidence for pulmonary embolism. Despite the low flow rate, a clear enhancement of the pulmonary artery was observed (up to 460 HU) (Fig. 1). Such an enhancement of the pulmonary artery is normally only achieved when injecting contrast at a flow rate of 4-5 ml/s. These perfect images, obtained at a low contrast flow rate in fact indicate severely impaired right ventricular function.

Experimental investigation of bubble growth from orifice plates submerged in pools of viscous liquids has been carried out using high speed videography. Conflicting effects of viscosity on ebullience have been reported in the literature. These are addressed in the present study and their range of applicability has been identified. Furthermore, the effects of chamber volume on bubble dynamics in viscous media are examined. Orifice plates made of Acrylic glass (a hydrophilic surface) with varying orifice diameters from 0.813 mm to 1.500 mm, have been utilized. Additionally, bubble dynamics from a stainless steel capillary nozzle was captured and compared with that from orifice plates. The six different liquid pools were used, viz., pure distilled water, ethylene glycol, propylene glycol, and three different aqueous glycerol solutions. The aqueous glycerol solutions varied in viscosity from 48 cP to 128 cP. The flow rate was regulated such that the isolated bubble regime was encountered. For the smaller orifices, viscosity effects were present at all flow rates and the bubbles in water-glycerol solutions were much larger than those in pure water. However, for the larger orifice sizes, water-glycerol solutions produced bubbles that were larger than those in water only at high air flow rates. For larger orifice sizes, at low flow rates, there was no increase in bubble size in highly viscous water-glycerol solutions compared to pure water. In fact, with 1.5 mm diameter plate orifice, the bubbles for 128 cP water-glycerol solution were smaller than those in pure water at low air flow rates. When chamber effects were present, the bubbles in the more viscous medium differed in shape and size from those in pure water.

Soil mechanics is a powerful theoretical analysis tool in geotechnical engineering. The principle of effective stress is a basis of classic soil mechanics. However, it in fact is an approximated method. This is attributed to three factors. Firstly, the effective stress is an equilibrium equation rather than an independent state variable. Secondly, the effective stress is a variable controlled the deformation behavior and the shear strength of soil, but not the only one. Thirdly, the principle of effective stress is an equivalent method, but not an accurate one. The above viewpoints are justified in this paper as follows. Firstly, it is demonstrated that the soil is a variable and sensitive material. Thus, it is difficult to quantitatively describe soil behaviors by only one variable. Secondly, the definition and the comprehension of the effective stress are discussed. Finally, to deal with complex problems most frequently encountered in geotechnical engineering, two approaches are advised, i.e., choosing additional variables except for the effective stress and using the multi-factor theory.

The role of flow rates on flow patterns and saturation in high-permeability porous media

Canonical transformations and variational principles for fluid dynamics