Numerical simulation of streaming in high amplitude standing wave resonators

2003 ◽  
Vol 113 (4) ◽  
pp. 2282-2282
Author(s):  
Said Boluriaan ◽  
Philip Morris
Keyword(s):  
Numerical Simulation ◽  
Standing Wave ◽  
High Amplitude

scholarly journals Three-dimensional numerical simulation of stepped dropshaft with different step shapes

2020 ◽  
Author(s):  
Jingkang Sun ◽  
Shangtuo Qian ◽  
Hui Xu ◽  
Xiaosheng Wang ◽  
Jiangang Feng
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Standing Wave ◽  
Flow Rate ◽  
Effective Means ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Deep Tunnel ◽  
Rate Distribution ◽  
Tunnel System

Abstract The deep tunnel system is increasingly used worldwide for stormwater conveyance and storage, providing a robust and effective means of preventing urban waterlogging. In the system, the dropshaft with the function of conveying stormwater to the deep tunnels underground, often runs under conditions of high falling head and large discharge. Based on the standard stepped dropshaft, a blade-shaped stepped dropshaft was proposed in order to control the potential standing wave and improve discharge capacity. Its hydraulic characteristics in respect of flow pattern, flow rate distribution, time-averaged pressure and energy dissipation were investigated by numerical simulation. Compared with the standard stepped dropshaft, the blade-shaped stepped dropshaft generated a more uniform flow rate distribution in the radial direction, therefore effectively decreasing the height of the standing wave near the external wall. The negative pressure areas that easily existed on the vertical wall of steps were well controlled. The energy dissipation of the blade-shaped stepped dropshaft was as high as that of the standard stepped dropshaft. Therefore, the blade-shaped stepped dropshaft could be a preferable design for the deep tunnel system.

Turbulence driven by chromospheric evaporations in solar flares

2021 ◽  
Author(s):  
Wenzhi Ruan ◽  
Chun Xia ◽  
Rony Keppens
Keyword(s):  
Numerical Simulation ◽  
Standing Wave ◽  
Solar Flares ◽  
Fast Electron ◽  
Thermal Conduction ◽  
High Speed ◽  
Helmholtz Instability ◽  
Flare Loop ◽  
X Ray ◽  
Flare Loops

<p>Chromospheric evaporations are frequently observed at the footpoints of flare loops in flare events. The evaporations flows driven by thermal conduction or fast electron deposition often have high speed of hundreds km/s. Since the speed of the observed evaporation flows is comparable to the local Alfven speed, it is reasonable to consider the triggering of Kelvin-Helmholtz instabilities. Here we revisit a scenario which stresses the importance of the Kelvin-Helmholtz instability (KHI) proposed by Fang et al. (2016). This scenario suggests that evaporations flows from two footpoints of a flare loop can meet each other at the looptop and produce turbulence there via KHI. The produced KHI turbulence can play important roles in particle accelerations and generation of strong looptop hard X-ray sources. We investigate whether evaporation flows can produce turbulence inside the flare loop with the help of numerical simulation. KHI turbulence is successfully produced in our simulation. The synthesized soft X-ray curve demonstrating a clear quasi-periodic pulsation (QPP) with period of 26 s. The QPP is caused by a locally trapped, fast standing wave that resonates in between KHI vortices.</p><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div><div></div>

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