Search results for "Backflow"
showing 6 items of 6 documents
Residence time distribution of solid particles in a continuous, high-aspect-ratio multiple-impeller stirred vessel
2004
Abstract In this paper experimental information on the retention time distribution (RTD) of solid particles in a high-aspect-ratio vessel, stirred by three equally spaced Rushton turbines, is presented. The relevant data were obtained by a special technique named twin system approach (TSA) that greatly simplifies the handling of particle-laden streams and is therefore particularly suited for investigating particle RTD in flow systems. The technique fundamentals are first summarized, together with the data analysis procedure. This lastly requires a numerical deconvolution operation that is easily performed with the help of Z -transforms. Two different approaches for excluding the spurious co…
On backflow associated with oceanic and continental subduction
2021
SUMMARY A popular idea is that accretion of sediment at a subduction zone commonly leads to the formation of a subduction channel, which is envisioned as a narrow zone located above a subducting plate and filled with vigorously circulating accreted sediment and exotic blocks. The circulation can be viewed as a forced convection, with downward flow in the lower part of the channel due to entrainment by the subducting plate, and a ‘backflow’ in the upper part of the channel. The backflow is often cited as an explanation for the exhumation of high-pressure/low-temperature metamorphic rocks from depths of 30 to 50 km. Previous analyses of this problem have mainly focused on the restricted case …
Distributed estimation and control of water distribution networks by logical consensus
2014
In this study we present a methodology for backflow detec- tion through the interpretation of results from a network of Automatic Meter Reading. The approach is based on the so– called logical consensus theory and consists of a distributed failure detection and system reconfiguration. The effective- ness of the proposed method is showed through simulation within a prototypical water distribution network.
Burner backflow reduction in regeneration furnace
2011
In the present case from the steel industry, waste hydrochloric acid from the pickling process is regenerated using spray roasting. The process is driven by four burners placed symmetrically along the periphery of the cylindrical main section of the reactor. Severe problems with gas backflow and sintering of iron oxide inside the burner chamber have led to a complete shut down of the process 1-2 times every week, which is a frequency which significantly affects the productivity. In this study the influence of a kick-out on the gas flow in the vicinity of the burner chamber is investigated numerically. It is shown that the kick-out geometry creates a vortical low pressure region preventing t…
Temperature effects on quantum non-Markovianity via collision models
2018
Quantum non-Markovianity represents memory during the system dynamics, which is typically weakened by the temperature. We here study the effects of environmental temperature on the non-Markovianity of an open quantum system by virtue of collision models. The environment is simulated by a chain of ancillary qubits that are prepared in thermal states with a finite temperature $T$. Two distinct non-Markovian mechanisms are considered via two types of collision models, one where the system $S$ consecutively interacts with the ancillas and a second where $S$ collides only with an intermediate system $S'$ which in turn interacts with the ancillas. We show that in both models the relation between …
Stratification of polymer mixtures in drying droplets: Hydrodynamics and diffusion
2020
We study the evaporation-induced stratification of a mixture of short and long polymer chains in a drying droplet using molecular simulations. We systematically investigate the effects of hydrodynamic interactions (HI) on this process by comparing hybrid simulations accounting for HI between polymers through the multiparticle collision dynamics technique with free-draining Langevin dynamics simulations neglecting the same. We find that the dried supraparticle morphologies are homogeneous when HI are included but are stratified in core--shell structures (with the short polymers forming the shell) when HI are neglected. The simulation methodology unambiguously attributes this difference to th…