Fluid Dynamical Systems Research Articles

A general formulation of the reversible stress tensor for a nonlocal fluid

The nonlocal stress tensor is an indispensable constitutive equation required to close the thermodynamic system of nonlocal fluid dynamics. A nonlocal functional variational principle is employed to derive a general expression for the thermodynamically reversible stress tensor for a two-phase, single component, nonlocal fluid. The Euler–Lagrange equation and Noether’s current are used to obtain the general form of the stress tensor, which is then used to derive a wide range of functional forms found in the literature. We also clarify some existing ambiguities. The general form of the nonlocal stress tensor is able to represent micro scale intermolecular interactions, and provides an efficient mesoscale numerical tool for multi-scale analysis using Lattice Boltzmann simulation.

New applications of quantum algebraically integrable systems in fluid dynamics

Rational quantum algebraically integrable systems are non-trivial generalizations of Laplacian operators to the case of elliptic operators with variable coefficients. We study corresponding extensions of Laplacian growth connected with algebraically integrable systems, describing viscous free-boundary flows in non-homogenous media. We introduce a class of planar flows related with application of Adler-Moser polynomials and construct solutions for higher-dimensional cases, where the conformal mapping technique is unavailable.

Pontryagin's Principle of Mixed Control-State Constrained Optimal Control Governed by Fluid Dynamic Systems

This article deals with Pontryagin's minimum principle for optimal control problems governed by an abstract fluid dynamical system with mixed control-state constraints. Two techniques are mainly used to obtain our results: ϵ-perturbation for admissible control set and diffuse perturbation for admissible control. Using these results, the necessary conditions for L 2-local optimal solution of our control problems can be studied under some assumptions. In the end of this article, these results are applied to some special fluid dynamical systems which contain the fluid systems driven by its boundary and magnetohydrodynamics(MHD).

Multiscale Simulation of Agglomerate Breakage in Fluidized Beds

In this contribution a multiscale simulation strategy is proposed which is able to simulate an industrial scale fluidized bed spray agglomeration process considering the breakage of agglomerates. A set of novel simulation approaches and hierarchically distributed models were developed and implemented into the multiscale simulation environment for solids processes. The population balance model (PBM) was used for the simulation of the global production process on the macroscale. On the microscale the coupling between discrete element method (DEM) and the computational fluid dynamics (CFD) system was employed to calculate the particle dynamics in the granulator. The material-based parameters for the PBM, such as breakage probability and breakage function, were derived from the process description on the lowest hierarchical scale, where the agglomerate was described as a system of primary particles bonded by a solid binder.

On alternative Poisson brackets for fluid dynamical systems and their extension to Stokes-Dirac structures

In this paper we shall consider the Hamiltonian formulation of one-dimensional models of fluid dynamical systems such as the Korteweg de Vries equation and the Boussinesq equation and their extension to port-Hamiltonian systems. We consider the Korteweg de Vries equation and recall its bi-Hamiltonian structure, either formulated as a single conservation law or formulated with respect to Magri's bracket. In both cases we give an extension of the associated Hamiltonian operators to a Stokes-Dirac structure. Then we consider the Boussinesq equation and recall the two Hamiltonian representations either with respect to the canonical Hamiltonian operator associated with a system of two coupled conservation laws or with respect to a third order Hamiltonian operator. In this case we shall suggest a third Hamiltonian operator for which an extension to a Dirac structure is derived.

Multisensor System for Isotemporal Measurements to Assess Indoor Climatic Conditions in Poultry Farms

The rearing of poultry for meat production (broilers) is an agricultural food industry with high relevance to the economy and development of some countries. Periodic episodes of extreme climatic conditions during the summer season can cause high mortality among birds, resulting in economic losses. In this context, ventilation systems within poultry houses play a critical role to ensure appropriate indoor climatic conditions. The objective of this study was to develop a multisensor system to evaluate the design of the ventilation system in broiler houses. A measurement system equipped with three types of sensors: air velocity, temperature and differential pressure was designed and built. The system consisted in a laptop, a data acquisition card, a multiplexor module and a set of 24 air temperature, 24 air velocity and two differential pressure sensors. The system was able to acquire up to a maximum of 128 signals simultaneously at 5 second intervals. The multisensor system was calibrated under laboratory conditions and it was then tested in field tests. Field tests were conducted in a commercial broiler farm under four different pressure and ventilation scenarios in two sections within the building. The calibration curves obtained under laboratory conditions showed similar regression coefficients among temperature, air velocity and pressure sensors and a high goodness fit (R2 = 0.99) with the reference. Under field test conditions, the multisensor system showed a high number of input signals from different locations with minimum internal delay in acquiring signals. The variation among air velocity sensors was not significant. The developed multisensor system was able to integrate calibrated sensors of temperature, air velocity and differential pressure and operated succesfully under different conditions in a mechanically-ventilated broiler farm. This system can be used to obtain quasi-instantaneous fields of the air velocity and temperature, as well as differential pressure maps to assess the design and functioning of ventilation system and as a verification and validation (V&V) system of Computational Fluid Dynamics (CFD) simulations in poultry farms.

Mechanism of petroleum migration and accumulation in western China’s superposed basins

In western China, most petroliferous basins are superposed due to their multi-periodic tectonic evolution, and the mechanisms of petroleum migration and accumulation are so complex that much more sophisticated methodologies are necessary for depiction of these mechanisms and identification of petroleum occurrences. For this purpose, in this article, a new methodology was formulated which includes: (1) vertical identification of petroleum migration and accumulation fluid dynamic systems in the superposed basins; (2) analysis of the effect of large scale regional faults and fault combinations on the fluids exchange between the vertically identified different systems; (3) analysis of petroleum migration and accumulation in each vertically identified system, and establishment of appropriate geological model of petroleum migration and accumulation for each vertically identified system. Using this methodology, the satisfactory results obtained in the Lunnan Uplift of Tarim Basin and Ludong Uplift of Jungar Basin case studies are: (1) existence of different vertical fluid dynamic systems in western China’s superposed basins which are very necessary for understanding the mechanism of petroleum migration and accumulation; (2) in deep system, long-distance lateral petroleum migration and accumulation mainly take place along the long time exposed unconformity with weathered, fractured or karst reservoir rocks; (3) regional faults are the main conducts for fluids migration from deep system up to middle and/or upper systems. As to middle and/or upper systems, regional faults play a role of “petroleum source”. Small faults within middle and/or upper systems conduct petroleum to carrier beds with less impeding force; (4) petroleum migrated from deep system vertically up to middle and/or upper systems will migrate laterally in carrier beds of these systems and accumulate to form pools near or far from faults.

Directional integration on unstructured meshes via supermesh construction

Unstructured meshes are in widespread use throughout computational physics, but calculating diagnostics of simulations on such meshes can be challenging. For example, in geophysical fluid dynamics, it is frequently desirable to compute directional integrals such as vertical integrals and zonal averages; however, it is difficult to compute these on meshes with no inherent spatial structure. This is widely regarded as an obstacle to the adoption of unstructured mesh numerical modelling in this field. In this paper, we describe an algorithm by which one can exactly compute such directional integrals on arbitrarily unstructured meshes. This is achieved via the solution of a problem of computational geometry, constructing the supermesh of two meshes. We demonstrate the utility of this approach by applying it to a classical geophysical fluid dynamics system: the thermally driven rotating annulus. This addresses an important objection to the more widespread use of unstructured mesh modelling.

Krylov‐accelerated algebraic multigrid for semi‐definite and nonsymmetric systems in computational fluid dynamics

SUMMARYThis article reports on experiences with aggregation algebraic multigrid relying on Krylov acceleration on each level of the grid hierarchy as preconditioners for linear systems in general purpose fluid flow simulation software. In benchmarks that reflect the requirements of industrial simulations, it is demonstrated that for semi‐definite problems, the performance of recently published algorithms of this type is very attractive but that proposed variants of these algorithms occasionally fail for nonsymmetric problems. A modification leading to reliable solvers is suggested. Copyright © 2012 John Wiley & Sons, Ltd.

Fluid dynamics processes at the Central Sakhalin fault (based on observations of the Yuzhno-Sakhalinsk mud volcano)

The Yuzhno-Sakhalinsk mud volcano is located in the southern part of the Sakhalin Island within the area of the Central Sakhalin fault, one of the largest disjunctive dislocations of the island. The volcano was monitored during field seasons in the period from 2005 to 2007, and data on flow rates, chemical and isotope compositions of gases, temperature and chemical composition of watermud mixture in the volcano’s blowouts were collected and analysed. During the observation period, seismic activity in the region under study was significantly variable in time and space. The monitoring results revealed «traces» of two earthquakes in the blowout activity of the Yuzhno-Sakhalinsk mud volcano – the Gornazavodsk earthquake, that took place on 17 (18) August 2006, and the Nevelsk earthquake of 2 August 2007. Based on results of our analyses of the field data and mathematical simulation data, it is possible to conclude that an additional inflow of «deep geofluids» could not have been a major trigger of the activity of the volcano after the earthquakes. In our opinion, all the observed anomalies may result from «water – rock – gas» interactions in the top part of the mud volcano’s feeder channel. A combination of water and gas flows in the volcano’s channel and silica-alumina rocks comprises a specific geochemical system that is sensitive to external (seismic) impacts. Therefore, comprehensive consideration of physical and chemical processes within fluid-dynamic systems is required for assurance of correct interpretation of empirical data.

Multi-Scale Positioning Control Model of a Novel Fluid Dynamic Drive by Coupling Process and Adapted CFD Models

In this paper multi-scale modeling of a novel fluid dynamic planar positioning system is described and compared with a simplified plant model. The multi-scale model is realized by coupling a mechatronic simulation model implemented in Matlab/Simulink and a transient 2D-CFD model realized with the Finite Element-software Ansys using the Flotran solver. The complex behavior of the fluidic system between two control tasks could be observed. The permission for large movements of the slide is solved using an appropriate remeshing concept.

A Low Mach Number Limit of a Dispersive Navier–Stokes System

We establish a low Mach number limit for classical solutions over the whole space of a compressible fluid dynamic system that includes dispersive corrections to the Navier–Stokes equations. The limiting system is similar to a ghost effect system [Y. Sone, Kinetic Theory and Fluid Dynamics, Model. Simul. Sci. Eng. Technol., Birkhauser, Boston, 2002]. Our analysis builds upon the framework developed by Metivier and Schochet [Arch. Ration. Mech. Anal., 158 (2001), pp. 61–90] and Alazard [Arch. Ration. Mech. Anal., 180 (2006), pp. 1–73] for nondispersive systems. The strategy involves establishing a priori estimates for the slow motion as well as a priori estimates for the fast motion. The desired convergence is obtained by establishing the local decay of the energy of the fast motion.

A Stream Function Approach to Optical Flow with Applications to Fluid Transport Dynamics

AbstractOptical flow is one of the classical problems in computer vision, but it has recently also been adapted to applications from other fields, such as fluid mechanics and dynamical systems. If the goal is to analyze the dynamics of system whose evolution is governed by a flow field that is the gradient of a potential function – which describes many flows in fluid dynamics – it is natural to approach the optical flow problem by reconstructing the potential function, also called the stream function, rather than reconstructing the components of the flow directly. This alternate approach allows one to impose scientific priors, via regularization, directly on the flow itself rather than on its components independently. We demonstrate the stream function formulation of optical flow and its application to reconstructing an oceanic fluid flow driven by satellite measurements. It is also shown how these flow fields can be used to analyze mixing and mass transport in the fluid system being imaged. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Investigation of Size Effects to the Mixing Performance on the X-shaped Micro-Channels

Due to the developing of micro-electro-mechanical-system, MEMS, the fabrication of the microminiaturization devices becomes obviously important. The advances in the basic understanding of fluid physics have opened an era of application of fluid dynamics systems using microchannels. The purpose of this study is to research the flow transport phenomenon by employing different kinds of micro-channel sizing in X-shaped micro-channels. As the working fluid, water is injected to microchannel at different mass flow rate. Over a wide range of flow condition, 1.06 < Re < 514, in X-shaped micro-channels, the mixture performances of numerical simulation, flow visualization, and temperature distribution remain the same. At the same mass flow rate as the Reynolds number below 112.53, the biggest channel size had the slowest flow velocity and got the best mixing performance; as the Reynolds number above 112.53, the smaller the channel sizing, the lower the pressure drops and the faster velocity becomes. The transition form early from laminar flow, the unsteady flow is an advantage for mixing in the limited mixing area, therefore 0.7 mm got the best mixing performance. It is clear that the size of the channel plays an important role in the X-shaped micro-channels.

The numerical simulation of vanadium RedOx flow batteries

In this article a theoretical model of a RedOx flow cell (RFC), based on an equation system of fluid dynamics and of electrochemistry, is presented. A numerical algorithm of the solution of the equation system is developed. The results of numerical simulation of processes in the RFC are analyzed and validated in a test cell. The effects of different electrode collectors and current densities on the operation of the RFC are studied.

Transonic Aeroelastic Instability Searches Using Sampling and Aerodynamic Model Hierarchy

DOI: 10.2514/1.J050509 A hierarchy of flow models is exploited for transonic aeroelastic stability analysis using the kriging interpolation technique applied within the Schur complement eigenvalue framework. In the Schur framework, a modified structural eigenvalue problem describes the coupled aeroelastic system with a precomputed interaction term depending on the response frequency. The interaction term, representing the influence of the high-dimensional computational fluid dynamics system, is approximated by reconstruction based on samples that can be computed using a frequency or time domain solver. The computationally cheap approximation model is developed and discussed in this paper for two-degree-of-freedom aerofoil cases. The approximation model is used for both the parametric blind search of aeroelastic instability and for updating predictions based on aerodynamic models of different fidelities.

Formation of dust ion-acoustic solitary waves in a dusty plasma with two-temperature trapped electrons

Formation of large amplitude dust ion-acoustic (DIA) solitary waves are investigated in a multicomponent dusty plasma whose constituents are warm ions, two-temperature trapped electrons and negatively charged dust grains. The fluid dynamical system of equations governing the dynamics of DIA waves is reduced to a pseudo energy-balance equation. The existence and basic properties of arbitrary amplitude DIA solitary waves are thus investigated via a Sagdeev potential approach. It is shown that the solitary structures are significantly affected by low- and high-temperature trapped electrons, as well as by ion temperature. It is also found that only positive potential DIA solitary structures are observed in such a plasma.

1912 DETECTION OF CIRCULATING PROSTATE CANCER CELLS BY MEANS OF AN ANTIBODY-CONJUGATED NANOPARTICULAR BIOSENSOR

You have accessJournal of UrologyProstate Cancer: Detection and Screening1 Apr 20111912 DETECTION OF CIRCULATING PROSTATE CANCER CELLS BY MEANS OF AN ANTIBODY-CONJUGATED NANOPARTICULAR BIOSENSOR M. Raschid Hoda, Gerit Theil, Ekkehard Weber, Klaus Lücke, and Paolo Fornara M. Raschid HodaM. Raschid Hoda Halle, Germany More articles by this author , Gerit TheilGerit Theil Halle, Germany More articles by this author , Ekkehard WeberEkkehard Weber Halle, Germany More articles by this author , Klaus LückeKlaus Lücke Potsdam, Germany More articles by this author , and Paolo FornaraPaolo Fornara Halle, Germany More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.2050AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Currently existing techniques for the isolation of circulating tumor cells (CTC) in blood have experimental approaches. Nanoparticles as biosensors could allow a refinement of the method and possible clinical applicability of the CTC-isolation in cancer patients. METHODS In the framework of a translational project we evaluate the clinical application of a nano-scaled detector conjugated with anti-EpCAM antibody for the isolation of CTCs from peripheral blood of patients with prostate cancer. We reported on the results of preclinical testing. RESULTS The Nano-detector consists of a nano-gold particles loaded on a steel wire. This is coated with anti-EpCAM-AK. At first, the characterization of EpCAM expression in established PCa-cell lines DU 145, PC3 and LNCaP as models for various tumor entities was tested. Cytochemistry showed that all three established cell lines express EpCAM on their cell membrane. The next step was to determine the cell binding efficiency of an anti-EpCAM-functionalized Nano-detectors in the fluid-dynamic system. The cell-binding experiments with cell lines showed a sufficient covalent binding of cells to the detector. For the characterization of the bounded CTCs the multiplex RT-PCR (AdnaTestProstateCancerDetect) was used and the tumor antigens PSMA, PSA, and EGFR were detected. In another step, blood samples from 20 prostate cancer patients of different stages were studied. These blood samples were used in the fluid dynamic system. The characterization of isolated cells was carried out on the RT-PCR with regard to the marker PSMA, PSA, EGFR and at cytochemical level on the detection of EpCAM expression and the control CD45-staining. These were isolated on average of 42.9 CTCs/7.5ml blood sample and in hrPCa, and 3.4 CTCc/7.5ml blood in organ-confined PCA. CONCLUSIONS Isolation of CTCs using an antibody-conjucated nano-scaled-detector in blood of prostate cancer patients of different stages is feasible with high efficiency. The first in-vivo use of this system is currently being tested clinically. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e764-e765 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information M. Raschid Hoda Halle, Germany More articles by this author Gerit Theil Halle, Germany More articles by this author Ekkehard Weber Halle, Germany More articles by this author Klaus Lücke Potsdam, Germany More articles by this author Paolo Fornara Halle, Germany More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Laminar flame and acoustic waves in two-dimensional flow

The complete system of fluid dynamics equations describing the development of instability of a reaction front in a two-dimensional flow in reversed time are reduced to a closed system of equations of front dynamics by using Lagrangian variables and integrals of motion. The system can be used to analyze processes behind the front without solving the complete system of fluid dynamics and chemical kinetics equations. It is demonstrated how the gas density disturbances induced by the moving front can be described in the adiabatic approximation.

Modeling of Fluid Dynamics and Thermo-Chemical System in Halogen Lamp Operation

One of the key elements in improving lamp efficiency is understanding and controlling the halogen transport process. Therefore, it is worthwhile to build a model that depicts this process and can be applied to the study of various types of lamps. We examined the halogen transport process in a lamp by using a hybrid simulation model based on fluid dynamics and chemical equilibrium.