Search Results

You are looking at 1 - 10 of 126 items for :

  • "Hydrodynamics" x
  • All content x
Clear All

In this paper variational and analytical methods for the solution of multilinked contact mechanical problems of deformable solids and fluid have been considered. Numerical methods have been found cumbersome and inaccurate. In this connection a new accurate and quick variational-analytical method for the lubricant flow analysis has been developed.

Restricted access
Pollack Periodica
Authors: Marek Šutúš, Jaroslav Hrudka, Gergély Rózsa, Ivona Škultétyová, and Štefan Stanko

. The core of the work is the hydrodynamic simulations of the current in ANSYS Fluent. The research focused on creating a 3D model based on the drawing documentation in the space application, after creating the polygon computational network and entering

Restricted access

In this paper, we present detailed experimental and modeling studies of a recently developed triphasic segmented flow millireactors for rapid nanoparticle-catalyzed gas–liquid reactions. We first present detailed observations of the hydrodynamics and flow regimes in a pseudo-biphasic mode of operation, which enable the design and selection of optimal operating conditions for the triphasic millireactor. We particularly focus on and analyze the presence of wetting films of the organic phase on the reactor walls at high flow speeds, a consequence of the phenomenon of forced wetting, which is a key ingredient for optimal reactor performance. Next, we describe the development of a simple phenomenological model, incorporating the key mass transport steps that accurately captures the observed experimental trends for the rhodium nanoparticle (RhNP) catalyzed hydrogenation of a model substrate (1-hexene). We further discuss and analyze the consequences of this model.

Restricted access

biofilm reactor , Journal of Hydrodynamics, Ser. B , Vol. 26 No. 4 , 2014 , pp. 664 ‒ 667 . [10] Hussain S. A. , Idris A. Spiral

Restricted access

Summary  

In order to evaluate the transport of 3H and 137Cs radionuclides in semi-closed brackish Lake Obuchi, Japan, bordered by nuclear fuel cycling facilities, a 3D-lower-trophic eco-hydrodynamic model has been developed and validated. In a short-term prediction, 3H and 137Cs activity levels in water should be in an agreement with field measurements. It became clear that the results depended on the mixing of fresh water and seawater in the model. Moreover, a short-term simulation estimated that most 3H and 137Cs flowed to the ocean rather than remaining in the lake. Based on calculations over the past 50 years, a peak of 137Cs in sediment was in 1963, when the maximum 137Cs fallout was observed. The calculation showed a rapid decrease after that peak, however, the field measurement data gradually declined. This suggested that the process by which 137Cs accumulated from the watershed to the lake was actually slower in the field than in the model calculations. The model may be successfully applied to a variety of different environmental situations as a generic tool for evaluating the concentration and migration of 3H and 137Cs in a brackish lake.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Varga, Z. Németh, J. Somlai, I. Varga, R. Szánthó, J. Borszéki, P. Halmos, J. Schunk, and P. Tilky

Abstract  

During the optimization of the AP-CITROX decontamination technology the effect of the different flow rates of the decontamination solutions on the radioactive contamination and corrosion state of stainless steel tube samples originating from steam generators of Paks NPP were studied by a pilot-plant circulation system. The results have proved that a significant increase (up to 2.89 m/s) in the flow rate of the decontamination solution in the 1-5 steps is highly recommended and in order to improve the passivity of the surfaces it should be kept as low as possible (0.5 m/s) during the passivation.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: G. Mrevlishvili, M. Sottomayor, M. Ribeiro da Silva, T. Mdzinarashvili, M. Al-Zaza, M. Tediashvili, D. Tushishvili, and N. Chanishvili

Abstract  

Bacterial viruses genome- ds-DNA -expulsion from the phage capsid is induced by temperature and is not accompanied by heat effects (temperature interval 45–75°C). Thus the temperature induced ejection of genetic material from phages is predominantly entropic. ds-DNA output from the capsid increases the viscosity of the phage suspension at least 100 times. ds-DNA output from the capsid is accompanied by a significant change of partial volume. The disruption of 1mg of phage produces ΔV=1.3×10–9 m3 which corresponds to a volume increase of 200%. This produces exothermic heat effects in closed calorimetric cells, with free volume above the measured liquid. This paper deals with the study of the V-group, family T-even, E. Coli bacteria phage (named unphage). According to electron microscopic pictures, the geometrical parameters of this phage are 750×560 Å (from head) and 900 Å (from tail).

Restricted access

The aim of the study is to assess hydro-morphologic evolution of currently cut off meander for 3 river restoration scenarios during 10 days of bank-full discharge. To simulate hydro-morpho-dynamics, a numerical model with movable bed, R2DM is used. Results for scenario with partially opened meander indicate aggradation at inlet of meander and 10% decrease in flow rate. Scenario with fully opened meander shows aggradation at the inlet and 55% decrease in flow rate. Full diversion scenario results in formation of natural river landforms (point bars, cut banks, pools, riffles) and stabilization of river bed evolution.

Restricted access

Abstract  

A radiotracer study was carried out in a trickle bed reactor (TBR) independently filled with two different types of packing i.e., hydrophobic and hydrophilic. The study was aimed at to estimate liquid holdup and investigate the dispersion characteristics of liquid phase with both types of packing at different operating conditions. Water and H2 gas were used as aqueous and gas phase, respectively. The liquid and gas flow rates used ranged from 0.83 × 10−7–16.67 × 10−7 m3/s and 0–3.33 × 10−4 m3 (std)/s, respectively. Residence time distribution (RTD) of liquid phase was measured using 82Br as radiotracer and about 10 MBq activity was used in each run. Mean residence time (MRT) and holdup of liquid phase were estimated from the measured RTD data. An axial dispersion with exchange model was used to simulate the measured RTD curves and model parameters (Peclet number and MRT) were obtained. At higher liquid flow rates, the TBR behaves as a plug flow reactor, whereas at lower liquid flow rates, the flow was found to be highly dispersed. The results of investigation indicated that the dispersion of liquid phase is higher in case of hydrophobic packing, whereas holdup is higher in case of hydrophilic packing.

Restricted access

Abstract  

The phase transitions occurring in aqueous solutions of macromolecules and their complex structures (like order-disorder transitions in proteins or nucleic acids solutions) are usually accompanied by small changes in their specific partial volumes. If the quantity of these substances in the closed calorimetric vessels is relatively large (few mg) and if the phase transition is accompanied by a high change of specific partial volume (like in solution of bacteriophages),it is possible to detect some imaginary heat effects in the DSC calorimeters which have closed (sealed) vessels with free volume above the liquid.

Restricted access