scholarly journals AUTOMATIC CALIBRATION OF NUMERICAL TIDAL MODELS

1980 ◽  
Vol 1 (17) ◽  
pp. 144
Author(s):  
K.P. Holz ◽  
U. Januszewski
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Calibration Method ◽  
Trial And Error ◽  
Elbe River ◽  
One Dimensional ◽  
Tidal Waves ◽  
Standard Tool ◽  
The Elbe River ◽  
Good Agreement

Numerical models for the simulation of tidal waves in estuaries have "become a standard tool of coastal engineers. Before they can he applied to practical problems, they have to be calibrated against nature. The basis for calibration is normally a representative set of tidal curves (natural field data), which has to be reproduced by the numerical model. Generally, the calibration is performed by empirically tuning certain parameters, until a fairly good agreement between measured and calculated quantities is obtained. In most cases, this is a "trial-and error" process which may become very time-consuming, and which strongly depends on the intuition and experience of the user. In order to make the process of calibration more effective, and to ensure that the best possible agreement between nature and numerical model is achieved, a calibration method has been developed to determine the parameters of the numerical model automatically by means of a mathematical method of optimization. The method is applied to a one-dimensional numerical model of the Elbe River.

scholarly journals Edge Cooling of a Fuel Cell during Aerial Missions by Ambient Air

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1432
Author(s):  
Lev Zakhvatkin ◽  
Alex Schechter ◽  
Eilam Buri ◽  
Idit Avrahami
Keyword(s):  
Fuel Cell ◽  
Numerical Model ◽  
Wind Tunnel ◽  
Boundary Conditions ◽  
Air Temperature ◽  
Numerical Models ◽  
Heat Removal ◽  
Ambient Air ◽  
Experimental Setup ◽  
Good Agreement

During aerial missions of fuel-cell (FC) powered drones, the option of FC edge cooling may improve FC performance and durability. Here we describe an edge cooling approach for fixed-wing FC-powered drones by removing FC heat using the ambient air during flight. A set of experiments in a wind tunnel and numerical simulations were performed to examine the efficiency of FC edge cooling at various flight altitudes and cruise speeds. The experiments were used to validate the numerical model and prove the feasibility of the proposed method. The first simulation duplicated the geometry of the experimental setup and boundary conditions. The calculated temperatures of the stack were in good agreement with those of the experiments (within ±2 °C error). After validation, numerical models of a drone’s fuselage in ambient air with different radiator locations and at different flight speeds (10–30 m/s) and altitudes (up to 5 km) were examined. It was concluded that onboard FC edge cooling by ambient air may be applicable for velocities higher than 10 m/s. Despite the low pressure, density, and Cp of air at high altitudes, heat removal is significantly increased with altitude at all power and velocity conditions due to lower air temperature.

Simulating Post Punching Behaviour of RC Slab-Column Connections Using a Micro Model

2016 ◽  
Vol 846 ◽  
pp. 231-236
Author(s):  
Hui Zhong Xue ◽  
Hong Guan ◽  
Xin Zheng Lu ◽  
Yi Li
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Structural Response ◽  
Calibration Method ◽  
Failure Criteria ◽  
Micro Model ◽  
Structural Behaviour ◽  
Flat Plates ◽  
Rc Slab

Punching shear is a common failure mode occurring at the slab-column connection region of a reinforced concrete (RC) flat plate. Progressive collapse of RC flat plates poses a significant scientific question on the post punching behaviour of such a structural system. The challenge lies in the complex interactions amongst various internal actions including large unbalanced moments and shear forces. Existing numerical models are unable to differentiate the influence of each individual action within the connection region after punching occurs. Therefore, a new numerical model is required to model these actions individually as well as to evaluate their interrelationships. This paper thus aims to propose a numerical method to investigate the structural response of RC slab-column connections by using a micro model, based on a representative post punching failure experiment. In the micro model, concrete is simulated using solid elements whilst the reinforcement is modelled with truss elements. In this micro model, the constitutive laws and failure criteria of materials play a crucial role in describing the model’s structural behaviour. A typical structural response is discussed and a calibration method is established. Ultimately this study is expected to facilitate the development of an effective, yet simplified numerical model for future progressive collapse simulation of slab-column connections.

Spallation of Concrete under Dynamic Loading: Mesh Size Effect

2011 ◽  
Vol 50-51 ◽  
pp. 929-933
Author(s):  
L. Yuan ◽  
Tao Xu ◽  
Q. Xu
Keyword(s):  
Numerical Model ◽  
Dynamic Loading ◽  
Stress Wave ◽  
Numerical Models ◽  
Failure Process ◽  
Mesh Size ◽  
Engineering Structures ◽  
One Dimensional ◽  
Failure Patterns ◽  
Concrete Materials

Spallation of concrete under dynamic loading has been the hot issue of concern about civil engineering structures and protective engineering. In the present paper, the principle of propagation of stress wave and the induced spallation process along a one-dimensional bar and the RFPA-Dynamics code which considers the heterogeneity of the concrete materials are briefly introduced. In order to numerically investigate the effect of mesh size of numerical model on the computational results, the failure process of concrete with three mesh sizes under dynamic loads was numerically simulated using RFPA-Dynamics code. Numerical simulations show that the failure patterns of concrete with different mesh sizes under dynamic stress waves are different. It is found that for the numerical models with the same mechanical parameters, the smaller mesh size of the numerical model is, the longer propagation of stress wave delay, the smaller the compressive stress is, thus the greater the tensile stress is, and the number of cracks is increasing, in general, rupture is more serious. The accuracy of mesh is little to improve when the number of the grid increases to a certain value.

A New Calibration Method for FLCs in the M-K Frame-Work

2011 ◽  
Vol 341-342 ◽  
pp. 426-431
Author(s):  
Amir Ghazanfari ◽  
Ahmad Assempour
Keyword(s):  
Metal Forming ◽  
Calibration Method ◽  
Forming Limit ◽  
Experimental Point ◽  
Trial And Error ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Frame Work ◽  
Inhomogeneity Factor ◽  
Good Agreement

The main drawback of the method proposed by Marciniak and Kuczynski for prediction of the limit strains in sheet metal forming processes is requirement of an experimental point of the forming limit curve (FLC) in order to calibrate the curve. The purpose of this work is to introduce a new method to calibrate the FLC using the M-K model in which no experimental data is needed. To achieve this goal, many experimental FLCs were collected from the literature and the values of the initial inhomogeneity factors were determined for them with trial and error aproach. Using these data, an empirical law was developed to predict the value of inhomogeneity factor. The resultant curves show good agreement with the experiments.

scholarly journals FLUSHING PATTERN OF NON-REACTIVE EFFLUENTS

1970 ◽  
Vol 1 (12) ◽  
pp. 113
Author(s):  
Adel M. Kamel
Keyword(s):  
Numerical Model ◽  
Finite Difference ◽  
Temporal Variations ◽  
Phase Lag ◽  
Tidal Variation ◽  
One Dimensional ◽  
South Central ◽  
Reactive Liquid ◽  
Explicit Finite Difference ◽  
Good Agreement

In south central Louisiana non-reactive liquid effluents are introduced into man-made relatively straight prismatic canals which are comparatively narrow and have brackish watpr To study the flushing pattern of liquid effluents introduced into those canals (or eptuanes), a one-dimensional numerical model is considered for a simplified system consisting of a long straight gently sloping reach with a sinusoidal tidal variation at the mouth of the estuary, sinusoidal tidal v^iation with a phase lag and an attenuated amplitude at the upstream end, a variable inflow hydrograph, and a variable inflow or outflow. For this system, the continuity and momentum eauations are solved numerically by an explicit finite difference scheme. The output of the model describes the spatial and temporal variations in flow velocity (also in water depth and discharge) from which the flushing pattern is obtained for a liquid effluent introduced at any time during the tidal cycle at any section along the estuary. The numerical model is applied to Charenton drainage canal m south central Louisiana and good agreement is obtained between the velocities and stage elevations predicted from the model and recorded in the field. An IBIV 360/65 computer is utilized.

Longitudinal Dispersion in a Stream Calculated by One Dimensional Numerical Model

1983 ◽  
Vol 14 (1) ◽  
pp. 41-46
Author(s):  
Torulv Tjomsland
Keyword(s):  
Numerical Model ◽  
Field Measurements ◽  
Longitudinal Dispersion ◽  
One Dimensional ◽  
Water Stage ◽  
Good Agreement

A one-dimensional numerical model was used to simulate water stage and dispersion of matter in a stream. The calculated results show quite good agreement with field measurements.

scholarly journals Analysis of a Tubular Torsionally Resonating Viscosity–Density Sensor

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3036
Author(s):  
Daniel Brunner ◽  
Joe Goodbread ◽  
Klaus Häusler ◽  
Sunil Kumar ◽  
Gernot Boiger ◽  
...  
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Experimental Results ◽  
Static Case ◽  
Flow Loop ◽  
Actual Measurement ◽  
Wide Range ◽  
Laminar And Turbulent Flow ◽  
The Impact ◽  
Good Agreement

This paper discusses a state-of-the-art inline tubular sensor that can measure the viscosity–density ( ρ η ) of a passing fluid. In this study, experiments and numerical modelling were performed to develop a deeper understanding of the tubular sensor. Experimental results were compared with an analytical model of the torsional resonator. Good agreement was found at low viscosities, although the numerical model deviated slightly at higher viscosities. The sensor was used to measure viscosities in the range of 0.3–1000 mPa·s at a density of 1000 kg/m3. Above 50 mPa·s, numerical models predicted viscosity within ±5% of actual measurement. However, for lower viscosities, there was a higher deviation between model and experimental results up to a maximum of ±21% deviation at 0.3 mPa·s. The sensor was tested in a flow loop to determine the impact of both laminar and turbulent flow conditions. No significant deviations from the static case were found in either of the flow regimes. The numerical model developed for the tubular torsional sensor was shown to predict the sensor behavior over a wide range, enabling model-based design scaling.

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.

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