Control Volume | ScienceGate

We present our results of 3D CT/MRI brachytherapy (BT) planning in 115 patients with locally advanced cervical cancer T2b-3bN0-1M0. The aim of this study was to assess the differences in the visualization of tumor target volumes and risk organs during the 3D CT/MRI BT. The results of the study revealed that the use of MRI imaging for dosimetric planning of dose distribution for a given volume of a cervical tumor target was the best method of visualization of the soft tissue component of the tumor process in comparison with CT images, it allowed to differentially visualize the cervix and uterine body, directly the tumor volume. Mean D90 HR-CTV for MRI was 32.9 cm3 versus 45.9 cm3 for CT at the time of first BT, p = 0.0002, which is important for local control of the tumor process. The contouring of the organs of risk (bladder and rectum) through MRI images allows for more clearly visualizing the contours, which statistically significantly reduces the dose load for individual dosimetric planning in the D2cc control volume, і.є. the minimum dose of 2 cm3 of the organ of risk: D2cc for the bladder was 24.3 Gy for MRI versus 34.8 Gy on CT (p = 0.045); D2cc for the rectum - 18.7 Gy for MRI versus 26.8 Gy for CT (p = 0.046). This is a prognostically important stage in promising local control, which allows preventing manifestation of radiation damage.

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Supervisory Control System for Ship Damage Control: Volume 8 - User's Manual

10.21236/ada397815 ◽

2001 ◽

Author(s):

Ron Carbonari ◽

Mike Pilat ◽

David C. Wilkins ◽

Patricia A. Tatem ◽

Frederick W. Williams

Keyword(s):

Control System ◽

Supervisory Control ◽

Control Volume ◽

Damage Control ◽

Supervisory Control System

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A Real-Time Mathematical Model for Three-Dimensional Tidal Flow and Water Quality

Water Science & Technology ◽

10.2166/wst.1991.0154 ◽

1991 ◽

Vol 24 (6) ◽

pp. 171-177 ◽

Cited By ~ 1

Author(s):

Zeng Fantang ◽

Xu Zhencheng ◽

Chen Xiancheng

Keyword(s):

Mathematical Model ◽

Water Quality ◽

Real Time ◽

Control Volume ◽

Tidal Flow ◽

Three Dimensional ◽

River Estuary ◽

Pearl River Estuary ◽

Practical Application ◽

The Pearl River

A real-time mathematical model for three-dimensional tidal flow and water quality is presented in this paper. A control-volume-based difference method and a “power interpolation distribution” advocated by Patankar (1984) have been employed, and a concept of “separating the top-layer water” has been developed to solve the movable boundary problem. The model is unconditionally stable and convergent. Practical application of the model is illustrated by an example for the Pearl River Estuary.

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Numerical implementation of finite-element method of control volume using irregular mesh

Proceedings of the Mavlyutov Institute of Mechanics ◽

10.21662/uim2010.1.008 ◽

2010 ◽

Vol 7 ◽

pp. 98-108

Author(s):

Yu.A. Gafarova

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Delaunay Triangulation ◽

Complex Geometry ◽

Control Volume ◽

Test Case ◽

The Finite Element Method ◽

Irregular Mesh ◽

Discrete Analogues ◽

Element Method

To solve problems with complex geometry it is considered the possibility of application of irregular mesh and the use of various numerical methods using them. Discrete analogues of the Beltrami-Mitchell equations are obtained by the control volume method using the rectangular grid and the finite element method of control volume using the Delaunay triangulation. The efficiency of using the Delaunay triangulation, Voronoi diagrams and the finite element method of control volume in a test case is demonstrated.

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Mathematical model of multiphase flow propagation for the case of underwater pipeline damage

Multiphase Systems ◽

10.21662/mfs2019.2.020 ◽

2019 ◽

Vol 14 (2) ◽

pp. 142-147

Author(s):

S.R. Kildibaeva ◽

E.T. Dalinskij ◽

G.R. Kildibaeva

Keyword(s):

Oil And Gas ◽

Control Volume ◽

Hydrate Formation ◽

Initial Moment ◽

Hydrate Shell ◽

Surrounding Water ◽

Vertical Coordinate ◽

Associated Gas ◽

First Case ◽

Underwater Pipeline

The paper deals with the case of damage to the underwater pipeline through which oil and associated gas are transported. The process of oil and gas migration is described by the flow of a multiphase submerged jet. At the initial moment, the temperature of the incoming hydrocarbons, their initial velocity, the temperature of the surrounding water, the depth of the pipeline is known. The paper considers two cases of different initial parameters of hydrocarbon outflow from the pipeline. In the first case, the thermobaric environmental conditions correspond to the conditions of hydrate formation and stable existence. Such a case corresponds to the conditions of the hydrocarbons flow in the Gulf of Mexico. In the second case, hydrate is not formed. Such flows correspond to the cases of oil transportation through pipelines in the Baltic sea (for example, Nord stream–2). The process of hydrate formation will be characterized by the following dynamics of the bubble: first, it will be completely gas, then a hydrate shell (composite bubble) will begin to form on its surface, then the bubble will become completely hydrate, which will be the final stage. The integral Lagrangian control volume method will be considered for modeling the dynamics of hydrocarbon jet propagation. According to this method, the jet is considered as a sequence of elementary volumes. When modeling the jet flow, the laws of conservation of mass, momentum and energy for the components included in the control volume are taken into account. The equations are used taking into account the possible formation of hydrate. Thermophysical characteristics of hydrocarbons coming from the damaged pipeline for cases of deep-water and shallow-water pipeline laying are obtained. The trajectories of hydrocarbon migration, the dependence of the jet temperature and density on the vertical coordinate are analyzed.

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Sea stars generate downforce to stay attached to surfaces

Scientific Reports ◽

10.1038/s41598-021-83961-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mark Hermes ◽

Mitul Luhar

Keyword(s):

Body Shape ◽

Control Volume ◽

Water Channel ◽

Morphological Plasticity ◽

The Body ◽

Sea Star ◽

Sea Stars ◽

Hydrodynamic Loads ◽

Spherical Dome ◽

Star Models

AbstractIntertidal sea stars often function in environments with extreme hydrodynamic loads that can compromise their ability to remain attached to surfaces. While behavioral responses such as burrowing into sand or sheltering in rock crevices can help minimize hydrodynamic loads, previous work shows that sea stars also alter body shape in response to flow conditions. This morphological plasticity suggests that sea star body shape may play an important hydrodynamic role. In this study, we measured the fluid forces acting on surface-mounted sea star and spherical dome models in water channel tests. All sea star models created downforce, i.e., the fluid pushed the body towards the surface. In contrast, the spherical dome generated lift. We also used Particle Image Velocimetry (PIV) to measure the midplane flow field around the models. Control volume analyses based on the PIV data show that downforce arises because the sea star bodies serve as ramps that divert fluid away from the surface. These observations are further rationalized using force predictions and flow visualizations from numerical simulations. The discovery of downforce generation could explain why sea stars are shaped as they are: the pentaradial geometry aids attachment to surfaces in the presence of high hydrodynamic loads.

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Numerical Simulation of Intrachamber Processes in the Power Plant

Applied Sciences ◽

10.3390/app11114990 ◽

2021 ◽

Vol 11 (11) ◽

pp. 4990

Author(s):

Boris Benderskiy ◽

Peter Frankovský ◽

Alena Chernova

Keyword(s):

Numerical Simulation ◽

Power Plant ◽

Flow Structure ◽

Power Plants ◽

Control Volume ◽

Conjugate Problem ◽

Topological Features ◽

Gas Dynamic ◽

Calculation Results ◽

Volume Method

This paper considers the issues of numerical modeling of nonstationary spatial gas dynamics in the pre-nozzle volume of the combustion chamber of a power plant with a cylindrical slot channel at the power plant of the mass supply surface. The numerical simulation for spatial objects is based on the solution conjugate problem of heat exchange by the control volume method in the open integrated platform for numerical simulation of continuum mechanics problems (openFoam). The calculation results for gas-dynamic and thermal processes in the power plant with a four-nozzle cover are presented. The analysis of gas-dynamic parameters and thermal flows near the nozzle cover, depending on the canal geometry, is given. The topological features of the flow structure and thermophysical parameters near the nozzle cap were studied. For the first time, the transformation of topological features of the flow structure in the pre-nozzle volume at changes in the mass channel’s geometry is revealed, described, and analyzed. The dependence of the Nusselt number in the central point of stagnation on the time of the power plants operation is revealed.

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A New Formulation of Maxwell’s Equations

Symmetry ◽

10.3390/sym13050868 ◽

2021 ◽

Vol 13 (5) ◽

pp. 868

Author(s):

Simona Fialová ◽

František Pochylý

Keyword(s):

Numerical Methods ◽

Maxwell’S Equations ◽

Maxwell's Equations ◽

Control Volume ◽

Control Volume Method ◽

Integral Forms ◽

New Formulation ◽

Electrical Induction ◽

Volume Method ◽

Integral Identities

In this paper, new forms of Maxwell’s equations in vector and scalar variants are presented. The new forms are based on the use of Gauss’s theorem for magnetic induction and electrical induction. The equations are formulated in both differential and integral forms. In particular, the new forms of the equations relate to the non-stationary expressions and their integral identities. The indicated methodology enables a thorough analysis of non-stationary boundary conditions on the behavior of electromagnetic fields in multiple continuous regions. It can be used both for qualitative analysis and in numerical methods (control volume method) and optimization. The last Section introduces an application to equations of magnetic fluid in both differential and integral forms.

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Analysis of Soil Water Response to Grass Transpiration

Soil and Water Research ◽

10.17221/6510-swr ◽

2013 ◽

Vol 1 (No. 3) ◽

pp. 85-98

Author(s):

Dohnal Michal ◽

Dušek Jaromír ◽

Vogel Tomáš ◽

Herza Jiří

Keyword(s):

Soil Water ◽

Water Uptake ◽

Preferential Flow ◽

Water Movement ◽

Control Volume ◽

Water Pressure ◽

Lower Boundary ◽

Root Water Uptake ◽

Water Dynamics ◽

Soil Water Dynamics

This paper focuses on numerical modelling of soil water movement in response to the root water uptake that is driven by transpiration. The flow of water in a lysimeter, installed at a grass covered hillslope site in a small headwater catchment, is analysed by means of numerical simulation. The lysimeter system provides a well defined control volume with boundary fluxes measured and soil water pressure continuously monitored. The evapotranspiration intensity is estimated by the Penman-Monteith method and compared with the measured lysimeter soil water loss and the simulated root water uptake. Variably saturated flow of water in the lysimeter is simulated using one-dimensional dual-permeability model based on the numerical solution of the Richards’ equation. The availability of water for the root water uptake is determined by the evaluation of the plant water stress function, integrated in the soil water flow model. Different lower boundary conditions are tested to compare the soil water dynamics inside and outside the lysimeter. Special attention is paid to the possible influence of the preferential flow effects on the lysimeter soil water balance. The adopted modelling approach provides a useful and flexible framework for numerical analysis of soil water dynamics in response to the plant transpiration.

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