# The potential flow model for a storm is represented by the superposition of a sink and a vortex. The stream function can be written in the $(r, \theta)$ system as $\psi=-\frac{\Lambda}{2 \pi} \theta+\frac{\Gamma}{2 \pi} \ln r,$ where $\Lambda=\Gamma=100 \mathrm{~m}^{2} / \mathrm{s}$. Assume a constant air density of $1.2 \mathrm{~kg} / \mathrm{m}^{3}$. The gauge pressure at a distance of $100 \mathrm{~m}$ from the storm eye is (A) -\infty (B) $-\frac{1.2}{\pi^{2}}$ (C) $-\frac{1.2}{2 \pi^{2}}$ (D) $-\frac{1.2}{4 \pi^{2}}$

## Question ID - 156028 :- The potential flow model for a storm is represented by the superposition of a sink and a vortex. The stream function can be written in the $(r, \theta)$ system as $\psi=-\frac{\Lambda}{2 \pi} \theta+\frac{\Gamma}{2 \pi} \ln r,$ where $\Lambda=\Gamma=100 \mathrm{~m}^{2} / \mathrm{s}$. Assume a constant air density of $1.2 \mathrm{~kg} / \mathrm{m}^{3}$. The gauge pressure at a distance of $100 \mathrm{~m}$ from the storm eye is (A) -\infty (B) $-\frac{1.2}{\pi^{2}}$ (C) $-\frac{1.2}{2 \pi^{2}}$ (D) $-\frac{1.2}{4 \pi^{2}}$

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(D) $-\frac{1.2}{4 \pi^{2}}$

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Three identical eagles of wing span $s$ are flying side by side in a straight line with no gap between their wing tips. Assume a single horse shoe vortex model (of equal strength $\Gamma$ ) for each bird. The net downwash experienced by the middle bird is
(A) $\frac{\Gamma}{\pi s}$
(B) $\frac{\Gamma}{2 \pi s}$
(C) $\frac{\Gamma}{3 \pi s}$
(D) $\frac{4 \Gamma}{3 \pi s}$