Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rise time of spherical intruder in granular fluid   A model is developed to explain rise time of a spherical intruder placed in a
granular bed, which is considered as fluid. Phenomenon of rising intruder in a
granular bed is well known as Brazil nut effect. Radius of the intruder is
varied with $R_n = R_0 n, n = 1 .. 10$. An approximation for $t << \tau$ is
chosen in order to simplify the solution of second order differential equation
of intruder vertical position to obtain the rise time T. A non-physical
parameter $\alpha$ and also transformation from $T$ to $T'$ are needed to be
introduced in order to control the results to mimic reported experiment
qualitatively. Several forms of rise time $T_n$ and also transformed rise time
$T_n'$ against $n$ are presented and discussed.

16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
7
The categories of this paper are: hep-th