<s>
The	O
CFD-DEM	B-Algorithm
model	O
,	O
or	O
Computational	O
Fluid	O
Dynamics	O
/	O
Discrete	B-Algorithm
Element	I-Algorithm
Method	I-Algorithm
model	O
,	O
is	O
a	O
process	O
used	O
to	O
model	O
or	O
simulate	O
systems	O
combining	O
fluids	O
with	O
solids	O
or	O
particles	O
.	O
</s>
<s>
In	O
CFD-DEM	B-Algorithm
,	O
the	O
motion	O
of	O
discrete	O
solids	O
or	O
particles	O
phase	O
is	O
obtained	O
by	O
the	O
Discrete	B-Algorithm
Element	I-Algorithm
Method	I-Algorithm
(	O
DEM	O
)	O
which	O
applies	O
Newton	O
's	O
laws	O
of	O
motion	O
to	O
every	O
particle	O
,	O
while	O
the	O
flow	O
of	O
continuum	O
fluid	O
is	O
described	O
by	O
the	O
local	O
averaged	O
Navier	O
–	O
Stokes	O
equations	O
that	O
can	O
be	O
solved	O
using	O
the	O
traditional	O
Computational	O
Fluid	O
Dynamics	O
(	O
CFD	O
)	O
approach	O
.	O
</s>
<s>
OpenMP	O
has	O
been	O
shown	O
to	O
be	O
more	O
efficient	O
in	O
performing	O
coupled	O
CFD-DEM	B-Algorithm
calculations	O
in	O
parallel	O
framework	O
as	O
compared	O
to	O
MPI	B-Application
by	O
Amritkar	O
et	O
al	O
.	O
</s>
<s>
Generally	O
,	O
the	O
simulation	O
domain	O
is	O
divided	O
into	O
many	O
sub-domains	O
and	O
each	O
process	O
calculates	O
only	O
one	O
sub-domain	O
using	O
MPI	B-Application
passing	O
boundary	O
information	O
;	O
for	O
each	O
sub-domain	O
,	O
the	O
CPUs	O
are	O
used	O
to	O
solve	O
the	O
fluid	O
phase	O
while	O
the	O
general	O
purpose	O
GPUs	O
are	O
used	O
to	O
solve	O
the	O
movement	O
of	O
particles	O
.	O
</s>
<s>
The	O
computation	O
cost	O
of	O
CFD-DEM	B-Algorithm
is	O
huge	O
due	O
to	O
a	O
large	O
number	O
of	O
particles	O
and	O
small	O
time	O
steps	O
to	O
resolve	O
particle-particle	O
collisions	O
.	O
</s>
