<s>
In	O
the	O
field	O
of	O
numerical	B-General_Concept
analysis	I-General_Concept
,	O
particle	B-Algorithm
methods	I-Algorithm
discretize	O
fluid	O
into	O
particles	O
.	O
</s>
<s>
Particle	B-Algorithm
methods	I-Algorithm
enable	O
the	O
simulation	O
of	O
some	O
otherwise	O
difficult	O
types	O
of	O
problems	O
,	O
at	O
the	O
cost	O
of	O
extra	O
computing	O
time	O
and	O
programming	O
effort	O
.	O
</s>
<s>
Some	O
of	O
particle	B-Algorithm
methods	I-Algorithm
are	O
meshfree	B-Algorithm
methods	I-Algorithm
and	O
vice	O
versa	O
.	O
</s>
<s>
One	O
of	O
the	O
earliest	O
particle	B-Algorithm
methods	I-Algorithm
is	O
smoothed	B-Application
particle	I-Application
hydrodynamics	I-Application
,	O
presented	O
in	O
1977	O
.	O
</s>
<s>
In	O
the	O
1990s	O
a	O
new	O
class	O
of	O
particle	B-Algorithm
methods	I-Algorithm
emerged	O
.	O
</s>
<s>
The	O
reproducing	B-Algorithm
kernel	I-Algorithm
particle	I-Algorithm
method	I-Algorithm
(	O
RKPM	O
)	O
emerged	O
,	O
the	O
approximation	O
motivated	O
in	O
part	O
to	O
correct	O
the	O
kernel	O
estimate	O
in	O
SPH	O
:	O
to	O
give	O
accuracy	O
near	O
boundaries	O
,	O
in	O
non-uniform	O
discretizations	O
,	O
and	O
higher-order	O
accuracy	O
in	O
general	O
.	O
</s>
<s>
Notably	O
,	O
in	O
a	O
parallel	O
development	O
,	O
the	O
Material	B-Algorithm
point	I-Algorithm
methods	I-Algorithm
were	O
developed	O
around	O
the	O
same	O
time	O
which	O
offer	O
similar	O
capabilities	O
.	O
</s>
<s>
The	O
following	O
numerical	B-General_Concept
methods	I-General_Concept
are	O
generally	O
considered	O
to	O
fall	O
within	O
the	O
general	O
class	O
of	O
"	O
particle	O
"	O
methods	O
.	O
</s>
