Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Calculating groundwater response times for flow in heterogeneous porous
  media   Predicting the amount of time required for a transient groundwater response
to take place is a practical question that is of interest in many situations.
This time scale is often called the response time. In the groundwater hydrology
literature there are two main methods used to calculate the response time: (i)
both the transient and steady state groundwater flow equations are solved, and
the response time is taken to be amount of time required for the transient
solution to approach the steady solution within some tolerance; and (ii) simple
scaling arguments are adopted. Certain limitations restrict both of these
approaches. Here we outline a third method, based on the theory of mean action
time. We derive the governing boundary value problem for both the mean and
variance of action time for confined flow in two-dimensional heterogeneous
porous media. Importantly, we show that these boundary value problems can be
solved using widely available software. Applying these methods to a test case
reveals the advantages of the theory of mean action time relative to standard
methods.

18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys