scholarly journals Impact of Along-Valley Orographic Variations on the Dispersion of Passive Tracers in a Stable Atmosphere

Atmosphere ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 225 ◽  
Author(s):  
Julian Quimbayo-Duarte ◽  
Chantal Staquet ◽  
Charles Chemel ◽  
Gabriele Arduini
Keyword(s):  
Numerical Model ◽  
Thermal Structure ◽  
Valley Floor ◽  
Tracer Concentration ◽  
Passive Scalars ◽  
Alpine Valley ◽  
Evening Transition ◽  
Ventilation Efficiency ◽  
Passive Tracers ◽  
Valley Section

A numerical model is used to investigate the transport of passive tracers in an idealized Alpine valley during stable wintertime conditions after the evening transition. The valley is composed of an upstream-valley section, which opens on a narrower downstream valley section, which opens onto a plain. The ratio between the valley-floor widths of the upstream and downstream sections is either 4 (simulation P1) or 11.5 (P2). The change in the thermal structure of the atmosphere in the along-valley direction and over the plain leads to the development of an along-valley flow. This flow is up-valley in the upstream section during the first three hours of the P1 simulation, reversing to the down-valley direction afterwards, but remains up-valley during the six hours of the P2 simulation. The effect of wind dynamics on the dispersion of passive scalars is identified by tracking areas prone to stagnation, recirculation, and ventilation using the methodology developed by Allwine and Whiteman (1994). Zones identified as prone to stagnation are consistent with those of high tracer concentration in both simulations. The narrowing of the valley is found to significantly reduce ventilation in the upstream section, an observation quantified by a ventilation efficiency.

Influence of valley geometry on stability of an earth dam

2014 ◽  
Vol 51 (10) ◽  
pp. 1207-1217 ◽  
Author(s):  
Ashok K. Chugh
Keyword(s):  
Numerical Model ◽  
Continuum Mechanics ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Three Dimensional ◽  
Valley Floor ◽  
Earth Dam ◽  
Two Dimensional ◽  
Crest Length ◽  
Practical Implications

Influence of valley geometry on stability of an earth dam is assessed in terms of its static slope stability. Numerical model results for an earth dam sited in a trapezoidal valley are presented for two combinations of dam crest length and valley floor width. In one combination, the valley floor width is held constant and the slope of valley walls is varied; in the second combination, the dam crest length is held constant and the slope of valley walls is varied. The results for the two combinations are not the same. The results presented are from three-dimensional (3-D) and two-dimensional (2-D) continuum-mechanics-based numerical analyses and are in terms of factor of safety (FoS) and associated slip surface. Significant results include: (i) influence of valley geometry on FoS is minimal when valley floor width exceeds about five times the dam height; and (ii) ratio of 3-D to 2-D FoS can be in the range of 1.03 to 1.30 depending on the valley geometry. Practical implications of the results are included.

scholarly journals Fractal trajectories in a numerical model of the upper Indian Ocean

1994 ◽  
Vol 1 (1) ◽  
pp. 45-50 ◽  
Author(s):  
S. D. Meyers ◽  
J. F. Magnan ◽  
J. J. O'Brien
Keyword(s):  
Spectral Analysis ◽  
Numerical Model ◽  
Indian Ocean ◽  
Gravity Waves ◽  
Equatorial Zone ◽  
Geographic Locations ◽  
Model Domain ◽  
The Indian Ocean ◽  
Passive Tracers ◽  
Scaling Dimension

Abstract. A wind-driven numerical model of the Indian Ocean is used to examine the horizontal statistics of hundreds of passive tracers spread evenly over the model domain. The distribution covers several dynamically distinct regions, revealing a variety of Lagrangian behaviours associated with different geographic locations. In particular, a cluster of trajectories with scaling dimension as large as 1.3 exists throughout the equatorial zone. Spectral analysis of trajectory displacements indicates mixed Rossby-gravity waves are involved in the production of some fractal trajectories.

NUMERICAL MODEL TO SIMULATE THE EROSION ON THE SLOPE DUE TO OVERTOPPING

2010 ◽  
Vol 13 (3) ◽  
pp. 78-87
Author(s):  
Hoai Cong Huynh
Keyword(s):  
Numerical Model ◽  
Flow Model ◽  
Bed Load ◽  
Experiment Data ◽  
Step Method ◽  
Morphological Model ◽  
Load Transport ◽  
Bed Load Transport ◽  
The Finite Difference Method ◽  
Good Agreement

The numerical model is developed consisting of a 1D flow model and the morphological model to simulate the erosion due to the water overtopping. The step method is applied to solve the water surface on the slope and the finite difference method of the modified Lax Scheme is applied for bed change equation. The Meyer-Peter and Muller formulae is used to determine the bed load transport rate. The model is calibrated and verified based on the data in experiment. It is found that the computed results and experiment data are good agreement.

A numerical model to verify the communication between Gari and Peccia springs (Cassino, Central Italy)

2015 ◽  
Vol 35 ◽  
pp. 268-271
Author(s):  
Michele Saroli ◽  
Michele Lancia ◽  
Marco Petitta ◽  
Gabriele Scarascia Mugnozza
Keyword(s):  
Numerical Model ◽  
Central Italy

Thermal structure of the southern Apennines along the Val d'Agri-Bari transect

2014 ◽  
Vol 32 ◽  
pp. 3-6
Author(s):  
Stefania Candela ◽  
Stefano Mazzoli ◽  
Antonella Megna ◽  
Stefano Santini
Keyword(s):  
Thermal Structure ◽  
Southern Apennines

Challenges facing the farmers of Central Otago

2014 ◽  
Vol 76 ◽  
pp. 25-28
Author(s):  
D.R. Stevens ◽  
J.P. Garden
Keyword(s):  
New Zealand ◽  
Valley Floor ◽  
History Of ◽  
Iconic Status

The Central Otago region, with its cold winters and hot summers, and valley floors with uplift mountains is definitely "a world of difference". At the NZGA conference in Alexandra in 1966 John Hercus stated "Central Otago has a lure which sets it apart from the rest of New Zealand. Its characteristics of geology, topography and climate, its history of occupation and exploitation, its scenery at once forbidding and yet strangely fascinating - these features combine to cast a spell which few who have been exposed, can ever fully escape" (Hercus 1966). The region and its high country have an iconic status epitomised by the "Southern Man" stereotype. This places Central Otago deep in the psyche of the nation. With this goes a unique and significant set of conditions under which farming must take place. Not only does the region have the biophysical challenges of soils, water and climate to contend with, but a wider set of values, often imposed from elsewhere. Fifty years after that first conference we remain challenged. What are the opportunities in front of us and how should we best accommodate the challenge of maintaining a viable enterprise and at the same time, respecting the intense public and customer interest in our use of land and livestock? Central Otago and the associated high country of the Lakes district and McKenzie basin can be divided into three farming types. These are the valley floor irrigable type, the flat and downland dryland regions, and the high country. Each of these has challenges that are at times unique, but often overlap with problems faced in other regions.

Sign in / Sign up

Export Citation Format

Share Document