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An Evaluation Method for Tornado Missile Strike Probability with Stochastic Correlation
Yuzuru Eguchi,Takahiro Murakami,Hiromaru Hirakuchi,Soichiro Sugimoto,Yasuo Hattori 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.2
An efficient evaluation method for the probability of a tornado missile strike without usingthe Monte Carlo method is proposed in this paper. A major part of the proposed probabilityevaluation is based on numerical results computed using an in-house code, Tornado-bornemissile analysis code, which enables us to evaluate the liftoff and flight behaviors of unconstrainedobjects on the ground driven by a tornado. Using the Tornado-borne missileanalysis code, we can obtain a stochastic correlation between local wind speed and flightdistance of each object, and this stochastic correlation is used to evaluate the conditionalstrike probability, QV(r), of a missile located at position r, where the local wind speed is V. Incontrast, the annual exceedance probability of local wind speed, which can be computedusing a tornado hazard analysis code, is used to derive the probability density function,p(V). Then, we finally obtain the annual probability of tornado missile strike on a structurewith the convolutional integration of product of QV(r) and p(V) over V. The evaluationmethod is applied to a simple problem to qualitatively confirm the validity, and to quantitativelyverify the results for two extreme cases in which an object is located just in thevicinity of or far away from the structure.
Effects of aspect ratio on laboratory simulation of tornado-like vortices
Zhuo Tang,Delong Zuo,Darryl James,Yuzuru Eguchi,Yasuo Hattori 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.2
Experiments were conducted in a large-scale Ward-type tornado simulator to study tornado-like vortices. Both flow velocities and the pressures at the surface beneath the vortices were measured. An interpretation of these measurements enabled an assessment of the mean flow field as well as the mean and fluctuating characteristics of the surface pressure deficit, which is a manifestation of the flow fluctuation aloft. An emphasis was placed on the effect of the aspect ratio of the tornado simulator on the characteristics of the simulated flow and the corresponding surface pressure deficit, especially the evolution of these characteristics due to the transition of the flow from a single-celled vortex to a two-celled vortex with increasing swirl ratio.