Analyzing the tremor of the Holuhraun eruption 2014-2015 using tremor modelling

Author(s):  
Thoralf Dietrich ◽  
Eva P.S. Eibl

<p>The 2014-2015 Holuhraun eruption was the largest eruption in Iceland in the last 230 years. After magma ascended below <!-- Gibt es ein Paper das belegt, dass Magmaaufstieg den Dike getriggert hat? Ich denke, das ist eher Spekulation. Vllt. wäre es besser einfach zu sagen, „From ice-covered Bardarbunga an about 2 week long EQ migration …“ -->the Bárðarbunga volcano’s icecap, an about 2 week long lateral migration of earthquakes was observed; later interpreted as dike formation in 4km to 6km depth<!-- Noch die Tiefe (formation [in 4-6km depth]) mit reinbringen? --><!-- Ja kannst du machen. -->. An eruption started on 29<sup>th</sup> and 31<sup>st</sup> of August 2014 at Holuhraun. During dike formation and eruption a long-lasting seismic signal called tremor was recorded by seismometers in the area. Eruptive tremor emerged with the onset of the eruptions on 29<sup>th</sup> and 31<sup>st</sup> of August . Tremor sources were located and interpreted in the context of the fissure and the lava flow field. However, a complete geophysical model to explain these is missing. Our starting point is the model on tremor generation based on conduit wall vibrations exited by laminar flow<!-- Bitte anpassen. --> (B. Julian 1994) to replicate the observed tremor signals. We performed a grid search and compare it with other models. In the range of rock parameter tolerance, we present implied characteristics of frequency and amplitude of the signals, if the Julian model were used as explanation for the tremor signals.</p>

Author(s):  
Joana R.C. Voigt ◽  
Christopher W. Hamilton ◽  
Stephen P. Scheidt ◽  
Ulrich Münzer ◽  
Ármann Höskuldsson ◽  
...  
Keyword(s):  

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Fabio Nardecchia ◽  
Annalisa Di Bernardino ◽  
Francesca Pagliaro ◽  
Paolo Monti ◽  
Giovanni Leuzzi ◽  
...  

Computational fluid dynamics (CFD) is currently used in the environmental field to simulate flow and dispersion of pollutants around buildings. However, the closure assumptions of the turbulence usually employed in CFD codes are not always physically based and adequate for all the flow regimes relating to practical applications. The starting point of this work is the performance assessment of the V2F (i.e., v2¯ − f) model implemented in Ansys Fluent for simulating the flow field in an idealized array of two-dimensional canyons. The V2F model has been used in the past to predict low-speed and wall-bounded flows, but it has never been used to simulate airflows in urban street canyons. The numerical results are validated against experimental data collected in the water channel and compared with other turbulence models incorporated in Ansys Fluent (i.e., variations of both k-ε and k-ω models and the Reynolds stress model). The results show that the V2F model provides the best prediction of the flow field for two flow regimes commonly found in urban canopies. The V2F model is also employed to quantify the air-exchange rate (ACH) for a series of two-dimensional building arrangements, such as step-up and step-down configurations, having different aspect ratios and relative heights of the buildings. The results show a clear dependence of the ACH on the latter two parameters and highlight the role played by the turbulence in the exchange of air mass, particularly important for the step-down configurations, when the ventilation associated with the mean flow is generally poor.


1997 ◽  
Vol 58 (6) ◽  
pp. 449-454 ◽  
Author(s):  
Nicki F. Stevens ◽  
John B. Murray ◽  
Geoff Wadge

2021 ◽  
Author(s):  
Joana R. C. Voigt ◽  
et al.

Details about previous established links between emplacement conditions and lava types, data and methods, additional correlation results, and limitations.<br>


Aerospace ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 324
Author(s):  
Yinbo Mao ◽  
Ziyu Chen ◽  
Hui Li ◽  
Xinrong Su ◽  
Xin Yuan

This paper presents a novel theory regarding the blade loading and the passage flow field within general turbomachineries. The basic philosophy is to establish an analytical relation between the loading, the flow angle, and the blade geometry based on the conservation of energy. Detailed validations and analyses will be carried out to provide a general scope regarding the theory itself as well as its advantages and limitations in common applications. The paper includes the theoretical derivation of the target relation. The starting point is the standard RANS equations. From that, with the aid of the passage-average operator, the relation between the loading and the passage flow field is derived under the energy balance. Theoretical analyses regarding the validity of the relation are performed based on the simulation results and test data on different cascades. Discussions are conducted regarding the assumption and potential applications of the theory. Conclusions are drawn on the applicability of the theory to introduce its potential applications in general turbomachineries.


2012 ◽  
Vol 550-553 ◽  
pp. 2964-2967
Author(s):  
De Yu Luan ◽  
Shen Jie Zhou ◽  
Song Ying Chen

Abstract: The 3D flow field generated by a dual-impeller in the agitation of glycerin fluid was simulated using the commercial CFD package. The flow was modeled as laminar and a multiple reference frame (MRF) approach was used to solve the discretized equations of motion. The velocity profiles with a dual-impeller rotating at constant speed of 200r/min and at different layer clearances were obtained. By analysis to their axial and radial velocity vector plots and velocity distribution curves, it is found that the velocity distributions of the dual 6-bladed radial disc turbines (2-6DT) are better when the clearance is bigger or equal to the T/2, accompanied with the flow field pattern of parallel flow. Moreover,when the clearance is smaller or equal to the T/3, there are more advantages for 6-bladed radial disc turbines + pitch 4-bladed turbines (6DT+PTB) than other combinations,followed by the flow field pattern of connected flow.


Author(s):  
Oaki Iida ◽  
Yosuke Aono

Effects of system rotation are investigated on inhomogeneous flow where disturbances are transported from turbulent to non-turbulent flow field through advection and turbulent diffusion. With the body force on the fringe region, spectral method is used for inhomogeneous flow which is stirred at the bottom of the cuboid computational box. As a result, it is found that inertial waves with a constant helicity are transmitted in the direction perpendicular to the stirred surface, and parallel to rotational axis. In this study, the effects of system rotation on generation and propagation of wave are discussed.


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