# Draining bathtub geometry using TikZ

How can I draw this sketch using TikZ?

Has anyone done something similar?

• 1) next question is which hemisphere do you want since looking up a hole from a pole makes a difference, perhaps show us what you tried ? – KJO Mar 11 at 14:34
• I'm voting to close this question as off-topic because this is do-it-for-me question. – Raaja Mar 11 at 15:40

Welcome to TeX-SE! You can use parametric plots to get something of that sort.

\documentclass[tikz,border=3.14mm]{standalone}
\begin{document}
\begin{tikzpicture}
\foreach \X in {0,45,...,315}
{\draw[green!60!black] plot[variable=\x,domain=0:4,smooth,samples=51]
({10*\x+\X-40/(\x+0.2)}:\x);}
\foreach \X in {1,2}
\end{tikzpicture}
\end{document}


• Demonstrates the supposed Coriolis effect "There is an African country near the equator where entrepreneurs have set up two toilets, one just north of the equator, the other just south of it. For a fee, they will allegedly demonstrate that the toilets flush in opposite directions. It is only for show, however; there is no real effect. Yes, there is such a thing as the Coriolis effect, but it is not enough to dominate the flushing of a toilet" see scientificamerican.com/article/can-somebody-finally-sett – KJO Mar 11 at 15:00
• @KJO As long as they stir the water in the correct direction at either side of the equator, there will be an effect. ;-) – marmot Mar 11 at 15:02
• I think this is a "flush in the pan" type of question :-) p.s. its every 36 degrees – KJO Mar 11 at 15:03