Vertical turbulent mixing processes on ebb tides in partially mixed estuaries

1988 ◽  
Vol 26 (1) ◽  
pp. 51-66 ◽  
Author(s):  
J.R. West ◽  
K. Shiono
Keyword(s):  
Turbulent Mixing ◽  
Mixing Processes ◽  
Vertical Turbulent Mixing

Influence of turbulent mixing processes on new particle formation: first results

1997 ◽  
Vol 28 ◽  
pp. S27-S28 ◽  
Author(s):  
V. Jaenisch ◽  
F. Stratmann ◽  
P.H. Austin ◽  
D.A. Hegg
Keyword(s):  
Turbulent Mixing ◽  
Particle Formation ◽  
New Particle Formation ◽  
Mixing Processes ◽  
First Results

scholarly journals Modeling and Numerical Simulation of the Turbulent Two-Phase Jet Confined in the Cylindrical Channel

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Turbulent Mixing ◽  
Cylindrical Channel ◽  
Stationary Flow ◽  
Important Class ◽  
Two Dimensional ◽  
Mixing Processes ◽  
Two Phase ◽  
Immiscible Liquids ◽  
Cylindrical Coordinate ◽  
Ground Part

Mixing processes in the turbulent two-phase jet confined at some distance from the nozzle aremodeled and examined. Many natural and technical phenomena deal with the turbulent mixing and heattransfer in the jet of mutually immiscible liquids, which represent an important class of the modern multiphasesystems dynamics. The differential equations for axially symmetrical two-dimensional stationary flow and theintegral correlations in a cylindrical coordinate system are considered for the free heterogeneous jet confined atits initial or ground part in the cylindrical channel. Algorithm and the results obtained may be of interest for theresearch and industrial tasks, where the calculations of the turbulent mixing and heat transfer in multiphase jetdevices are of importance.

scholarly journals Role of eyewall and rainband eddy forcing in tropical cyclone intensification

2019 ◽  
Vol 19 (22) ◽  
pp. 14289-14310 ◽  
Author(s):  
Ping Zhu ◽  
Bryce Tyner ◽  
Jun A. Zhang ◽  
Eric Aligo ◽  
Sundararaman Gopalakrishnan ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Turbulent Mixing ◽  
Inner Core ◽  
Weather Research And Forecasting ◽  
Rapid Changes ◽  
Flow Feature ◽  
Secondary Circulations ◽  
Vertical Turbulent Mixing ◽  
Operational Models

Abstract. While turbulence is commonly regarded as a flow feature pertaining to the planetary boundary layer (PBL), intense turbulent mixing generated by cloud processes also exists above the PBL in the eyewall and rainbands of a tropical cyclone (TC). The in-cloud turbulence above the PBL is intimately involved in the development of convective elements in the eyewall and rainbands and consists of a part of asymmetric eddy forcing for the evolution of the primary and secondary circulations of a TC. In this study, we show that the Hurricane Weather Research and Forecasting (HWRF) model, one of the operational models used for TC prediction, is unable to generate appropriate sub-grid-scale (SGS) eddy forcing above the PBL due to a lack of consideration of intense turbulent mixing generated by the eyewall and rainband clouds. Incorporating an in-cloud turbulent-mixing parameterization in the vertical turbulent-mixing scheme notably improves the HWRF model's skills in predicting rapid changes in intensity for several past major hurricanes. While the analyses show that the SGS eddy forcing above the PBL is only about one-fifth of the model-resolved eddy forcing, the simulated TC vortex inner-core structure, secondary overturning circulation, and the model-resolved eddy forcing exhibit a substantial dependence on the parameterized SGS eddy processes. The results highlight the importance of eyewall and rainband SGS eddy forcing to numerical prediction of TC intensification, including rapid intensification at the current resolution of operational models.

scholarly journals Attributing differences in the fate of lateral boundary ozone in AQMEII3 models to physical process representations

2018 ◽  
Vol 18 (23) ◽  
pp. 17157-17175
Author(s):  
Peng Liu ◽  
Christian Hogrefe ◽  
Ulas Im ◽  
Jesper H. Christensen ◽  
Johannes Bieser ◽  
...  
Keyword(s):  
Turbulent Mixing ◽  
Dry Deposition ◽  
Gulf Coast ◽  
Vertical Mixing ◽  
Primary Role ◽  
Southeastern Us ◽  
The Us ◽  
Vertical Grid ◽  
Vertical Turbulent Mixing ◽  
The Impact

Abstract. Increasing emphasis has been placed on characterizing the contributions and the uncertainties of ozone imported from outside the US. In chemical transport models (CTMs), the ozone transported through lateral boundaries (referred to as LB ozone hereafter) undergoes a series of physical and chemical processes in CTMs, which are important sources of the uncertainty in estimating the impact of LB ozone on ozone levels at the surface. By implementing inert tracers for LB ozone, the study seeks to better understand how differing representations of physical processes in regional CTMs may lead to differences in the simulated LB ozone that eventually reaches the surface across the US. For all the simulations in this study (including WRF∕CMAQ, WRF∕CAMx, COSMO-CLM∕CMAQ, and WRF∕DEHM), three chemically inert tracers that generally represent the altitude ranges of the planetary boundary layer (BC1), free troposphere (BC2), and upper troposphere–lower stratosphere (BC3) are tracked to assess the simulated impact of LB specification. Comparing WRF∕CAMx with WRF∕CMAQ, their differences in vertical grid structure explain 10 %–60 % of their seasonally averaged differences in inert tracers at the surface. Vertical turbulent mixing is the primary contributor to the remaining differences in inert tracers across the US in all seasons. Stronger vertical mixing in WRF∕CAMx brings more BC2 downward, leading to higher BCT (BCT=BC1+BC2+BC3) and BC2∕BCT at the surface in WRF∕CAMx. Meanwhile, the differences in inert tracers due to vertical mixing are partially counteracted by their difference in sub-grid cloud mixing over the southeastern US and the Gulf Coast region during summer. The process of dry deposition adds extra gradients to the spatial distribution of the differences in DM8A BCT by 5–10 ppb during winter and summer. COSMO-CLM∕CMAQ and WRF∕CMAQ show similar performance in inert tracers both at the surface and aloft through most seasons, which suggests similarity between the two models at process level. The largest difference is found in summer. Sub-grid cloud mixing plays a primary role in their differences in inert tracers over the southeastern US and the oceans in summer. Our analysis of the vertical profiles of inert tracers also suggests that the model differences in dry deposition over certain regions are offset by the model differences in vertical turbulent mixing, leading to small differences in inert tracers at the surface in these regions.

Analysis and Optimization of Turbulent Mixing With Large Eddy Simulation

2006 ◽  
Author(s):  
Ying Huai ◽  
Amsini Sadiki
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Mixing ◽  
Optimization Procedure ◽  
Impinging Jet ◽  
Computational Domain ◽  
Original Design ◽  
Mixing Processes ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Practical Engineering

In this work, Large Eddy Simulation (LES) has been carried out to analyze the turbulent mixing processes in an impinging jet configuration. To characterize and quantify turbulent mixing processes, in terms of scalar structures and degree of mixing, three parameters have been basically introduced. They are “mixedness parameter”, which represents the probability of mixed fluids in computational domain, the Spatial Mixing Deficiency (SMD) and the Temporal Mixing Deficiency (TMD) parameters for characterizing the mixing at different scalar scale degrees. With help of these parameters, a general mixing optimization procedure has then been suggested and achieved in an impinging jet configuration. An optimal jet angle was estimated and the overall mixing degree with this jet angle reached around six times more than the original design. It turns out that the proposed idea and methodology can be helpful for practical engineering design processes.

Experimental Measurement of the Vortex Development Downstream of a Lobed Forced Mixer

1992 ◽  
Vol 114 (1) ◽  
pp. 63-71 ◽  
Author(s):  
W. A. Eckerle ◽  
H. Sheibani ◽  
J. Awad
Keyword(s):  
Secondary Flow ◽  
Turbulent Mixing ◽  
Large Scale ◽  
Vortex Breakdown ◽  
Velocity Ratio ◽  
Mixing Process ◽  
Mixing Processes ◽  
Design Variables ◽  
Secondary Motion ◽  
The Mean

An experimental study was conducted to investigate the mixing processes downstream of a forced mixer. A forced mixer generates large-scale, axial (stirring) vorticity, which causes the primary and secondary flow to mix rapidly with low loss. These devices have been successfully used in the past where enhanced mixing of two streams was a requirement. Unfortunately, details of the mixing process associated with these lobed forced mixers are not well understood. Performance sensitivity to design variables has not been documented. An experiment was set up to investigate the mixing processes downstream of a mixer. Air flow was independently supplied to each side of the forced mixer by separate centrifugal blowers. Pressures were measured at the entrance to the lobes with a pitot-static probe to document the characteristics of the approaching boundary layer. Interior mean and fluctuating velocities were nonintrusively measured using a two-component laser-Doppler velocimetry (LDV) system for velocity ratios of 1:1 and 2:1. The wake structure is shown to display a three-step process where initially secondary flow was generated by the mixer lobes, the secondary flow created counterrotating vortices with a diameter on the order of the convolute width, and then the vortices broke down resulting in a significant increase in turbulent mixing. The results show that the mean secondary motion induced by the lobes effectively circulated the flow passing through the lobes. This motion, however, did not homogeneously mix the two streams. Turbulent mixing in the third step of the mixing process appears to be an important element in the enhanced mixing that has been observed with forced mixers. The length required for the flow to reach this third step is a function of the velocity ratio across the mixer. The results of this investigation indicate that both the mean secondary motion and the turbulent mixing occurring after vortex breakdown need to be considered for prediction of forced mixer performance.

Particle nucleation and condensational growth during turbulent mixing processes

1998 ◽  
Vol 29 ◽  
pp. S1161-S1162 ◽  
Author(s):  
Volker Jaenisch ◽  
Frank Stratmann ◽  
Martin Wilck
Keyword(s):  
Turbulent Mixing ◽  
Particle Nucleation ◽  
Mixing Processes ◽  
Condensational Growth

Seasonal Cycle of the Mixed Layer Heat Budget in the Northeastern Tropical Atlantic Ocean

2013 ◽  
Vol 26 (20) ◽  
pp. 8169-8188 ◽  
Author(s):  
Gregory R. Foltz ◽  
Claudia Schmid ◽  
Rick Lumpkin
Keyword(s):  
Mixed Layer ◽  
Annual Cycle ◽  
Turbulent Mixing ◽  
Seasonal Cycle ◽  
Heat Budget ◽  
Heat Content ◽  
Boreal Summer ◽  
Tropical Atlantic ◽  
Mixed Layer Heat Budget ◽  
Vertical Turbulent Mixing

Abstract The seasonal cycle of the mixed layer heat budget in the northeastern tropical Atlantic (0°–25°N, 18°–28°W) is quantified using in situ and satellite measurements together with atmospheric reanalysis products. This region is characterized by pronounced latitudinal movements of the intertropical convergence zone (ITCZ) and strong meridional variations of the terms in the heat budget. Three distinct regimes within the northeastern tropical Atlantic are identified. The trade wind region (15°–25°N) experiences a strong annual cycle of mixed layer heat content that is driven by approximately out-of-phase annual cycles of surface shortwave radiation (SWR), which peaks in boreal summer, and evaporative cooling, which reaches a minimum in boreal summer. The surface heat-flux-induced changes in the mixed layer heat content are damped by a strong annual cycle of cooling from vertical turbulent mixing, estimated from the residual in the heat balance. In the ITCZ core region (3°–8°N) a weak seasonal cycle of mixed layer heat content is driven by a semiannual cycle of SWR and damped by evaporative cooling and vertical turbulent mixing. On the equator the seasonal cycle of mixed layer heat content is balanced by an annual cycle of SWR that reaches a maximum in October and a semiannual cycle of turbulent mixing that cools the mixed layer most strongly during May–July and November. These results emphasize the importance of the surface heat flux and vertical turbulent mixing for the seasonal cycle of mixed layer heat content in the northeastern tropical Atlantic.

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