Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mixing induced by a bubble swarm rising through incident turbulence   This work describes an experimental investigation on the mixing induced by a
swarm of high Reynolds number air bubbles rising through a nearly homogeneous
and isotropic turbulent flow. The gas volume fraction $\alpha$ and the velocity
fluctuations $u'_0$ of the carrier flow before bubble injection are varied,
respectively, in the ranges $0\leq \alpha \leq 0.93\%$ and 2.3 cm/s $\leq u'_0
\leq 5.5$ cm/s, resulting in a variation of the bubblance parameter $b$ in the
range [0, 1.3] ($b = \frac{V_r^2 \alpha}{{u'}_0^2}$, where $V_r$ is the
relative rising velocity). Mixing in the horizontal direction can be modelled
as a diffusive process, with an effective diffusivity $D_{xx}$. Two different
diffusion regimes are observed experimentally, depending on the turbulence
intensity. At low turbulence levels, $D_{xx}$ increases with gas volume
fraction $\alpha$, while at high turbulence levels the enhancement in $D_{xx}$
is negligible. When normalizing by the time scale of successive bubble passage,
the effective diffusivity can be modelled as a sole function of the gas volume
fraction $\alpha^* \equiv \alpha/\alpha_c$, where $\alpha_c$ is a theoretically
estimated critical gas volume fraction. The present explorative study provides
insights into modeling the mixing induced by high Reynolds number bubbles in
turbulent flows.

32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex