<s>
FEFLOW	B-Language
(	O
Finite	B-Application
Element	I-Application
subsurface	O
FLOW	O
system	O
)	O
is	O
a	O
computer	O
program	O
for	O
simulating	B-Application
groundwater	O
flow	O
,	O
mass	O
transfer	O
and	O
heat	O
transfer	O
in	O
porous	O
media	O
and	O
fractured	O
media	O
.	O
</s>
<s>
The	O
program	O
uses	O
finite	B-Application
element	I-Application
analysis	I-Application
to	O
solve	O
the	O
groundwater	O
flow	O
equation	O
of	O
both	O
saturated	O
and	O
unsaturated	O
conditions	O
as	O
well	O
as	O
mass	O
and	O
heat	O
transport	O
,	O
including	O
fluid	O
density	O
effects	O
and	O
chemical	O
kinetics	O
for	O
multi-component	O
reaction	O
systems	O
.	O
</s>
<s>
In	O
1990	O
he	O
was	O
one	O
of	O
the	O
founders	O
of	O
WASY	O
GmbH	O
of	O
Berlin	O
,	O
Germany	O
(	O
the	O
acronym	O
WASY	O
translates	O
from	O
German	O
to	O
Institute	O
for	O
Water	O
Resources	O
Planning	O
and	O
Systems	O
Research	O
)	O
,	O
where	O
FEFLOW	B-Language
has	O
been	O
developed	O
further	O
,	O
continuously	O
improved	O
and	O
extended	O
as	O
a	O
commercial	O
simulation	O
package	O
.	O
</s>
<s>
The	O
WASY	O
company	O
has	O
been	O
fused	O
and	O
FEFLOW	B-Language
became	O
part	O
of	O
the	O
DHI	O
Group	O
software	O
portfolio	O
.	O
</s>
<s>
FEFLOW	B-Language
is	O
being	O
further	O
developed	O
at	O
DHI	O
by	O
an	O
international	O
team	O
.	O
</s>
<s>
The	O
program	O
is	O
offered	O
in	O
both	O
32-bit	O
and	O
64-bit	B-Device
versions	O
for	O
Microsoft	B-Application
Windows	I-Application
and	O
Linux	B-Application
operating	I-Application
systems	I-Application
.	O
</s>
<s>
FEFLOW	B-Language
's	O
theoretical	O
basis	O
is	O
fully	O
described	O
in	O
the	O
comprehensive	O
FEFLOW	B-Language
book	O
.	O
</s>
<s>
The	O
book	O
starts	O
with	O
a	O
more	O
general	O
theory	O
for	O
all	O
relevant	O
flow	O
and	O
transport	O
phenomena	O
on	O
the	O
basis	O
of	O
the	O
continuum	O
mechanics	O
,	O
systematically	O
develops	O
the	O
basic	O
framework	O
for	O
important	O
classes	O
of	O
problems	O
(	O
e.g.	O
,	O
multiphase/multispecies	O
non-isothermal	O
flow	O
and	O
transport	O
phenomena	O
,	O
variably	O
saturated	O
porous	O
media	O
,	O
free-surface	O
groundwater	O
flow	O
,	O
aquifer-averaged	O
equations	O
,	O
discrete	O
feature	O
elements	O
)	O
,	O
introduces	O
finite	B-Application
element	I-Application
methods	I-Application
for	O
solving	O
the	O
basic	O
multidimensional	O
balance	O
equations	O
,	O
in	O
detail	O
discusses	O
advanced	O
numerical	O
algorithms	O
for	O
the	O
resulting	O
nonlinear	O
and	O
linear	O
problems	O
,	O
and	O
completes	O
with	O
a	O
number	O
of	O
benchmarks	O
,	O
applications	O
and	O
exercises	O
to	O
illustrate	O
the	O
different	O
types	O
of	O
flow	O
,	O
mass	O
and	O
heat	O
transport	O
problems	O
(	O
e.g.	O
,	O
subsurface	O
flow	O
and	O
seepage	O
problems	O
,	O
unsaturated-saturated	O
flow	O
,	O
advective-diffusion	O
transport	O
,	O
saltwater	O
intrusion	O
,	O
geothermal	O
and	O
thermohaline	O
flow	O
)	O
.	O
</s>
