velocity	concentration
2.1	1
2.5	1.5
4.9	2
5.5	3
7	4
8.4	5
9.6	6
10.2	7.5
11.4	8.5
12.5	10
13.1	12.5
14.6	15
17	17.5
16.8	20
18.6	25
19.7	30
21.3	35
21.6	40