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SWIFT
SWIFTsim
Commits
fe006ced
Commit
fe006ced
authored
8 years ago
by
Stefan Arridge
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Added energy conservation test to hydrostatic halo example
parent
730192c6
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2 merge requests
!272
Added README files to examples
,
!271
Stats include external potential energy
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examples/HydrostaticHalo/test_energy_conservation.py
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examples/HydrostaticHalo/test_energy_conservation.py
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fe006ced
import
numpy
as
np
import
h5py
as
h5
import
matplotlib.pyplot
as
plt
import
sys
n_snaps
=
101
#some constants
OMEGA
=
0.3
# Cosmological matter fraction at z = 0
PARSEC_IN_CGS
=
3.0856776e18
KM_PER_SEC_IN_CGS
=
1.0e5
CONST_G_CGS
=
6.672e-8
h
=
0.67777
# hubble parameter
gamma
=
5.
/
3.
eta
=
1.2349
H_0_cgs
=
100.
*
h
*
KM_PER_SEC_IN_CGS
/
(
1.0e6
*
PARSEC_IN_CGS
)
#read some header/parameter information from the first snapshot
filename
=
"
Hydrostatic_000.hdf5
"
f
=
h5
.
File
(
filename
,
'
r
'
)
params
=
f
[
"
Parameters
"
]
unit_mass_cgs
=
float
(
params
.
attrs
[
"
InternalUnitSystem:UnitMass_in_cgs
"
])
unit_length_cgs
=
float
(
params
.
attrs
[
"
InternalUnitSystem:UnitLength_in_cgs
"
])
unit_velocity_cgs
=
float
(
params
.
attrs
[
"
InternalUnitSystem:UnitVelocity_in_cgs
"
])
unit_time_cgs
=
unit_length_cgs
/
unit_velocity_cgs
v_c
=
float
(
params
.
attrs
[
"
IsothermalPotential:vrot
"
])
v_c_cgs
=
v_c
*
unit_velocity_cgs
header
=
f
[
"
Header
"
]
N
=
header
.
attrs
[
"
NumPart_Total
"
][
0
]
box_centre
=
np
.
array
(
header
.
attrs
[
"
BoxSize
"
])
#calculate r_vir and M_vir from v_c
r_vir_cgs
=
v_c_cgs
/
(
10.
*
H_0_cgs
*
np
.
sqrt
(
OMEGA
))
M_vir_cgs
=
r_vir_cgs
*
v_c_cgs
**
2
/
CONST_G_CGS
potential_energy_array
=
[]
internal_energy_array
=
[]
kinetic_energy_array
=
[]
time_array_cgs
=
[]
for
i
in
range
(
n_snaps
):
filename
=
"
Hydrostatic_%03d.hdf5
"
%
i
f
=
h5
.
File
(
filename
,
'
r
'
)
coords_dset
=
f
[
"
PartType0/Coordinates
"
]
coords
=
np
.
array
(
coords_dset
)
#translate coords by centre of box
header
=
f
[
"
Header
"
]
snap_time
=
header
.
attrs
[
"
Time
"
]
snap_time_cgs
=
snap_time
*
unit_time_cgs
time_array_cgs
=
np
.
append
(
time_array_cgs
,
snap_time_cgs
)
coords
[:,
0
]
-=
box_centre
[
0
]
/
2.
coords
[:,
1
]
-=
box_centre
[
1
]
/
2.
coords
[:,
2
]
-=
box_centre
[
2
]
/
2.
radius
=
np
.
sqrt
(
coords
[:,
0
]
**
2
+
coords
[:,
1
]
**
2
+
coords
[:,
2
]
**
2
)
radius_cgs
=
radius
*
unit_length_cgs
radius_over_virial_radius
=
radius_cgs
/
r_vir_cgs
r
=
radius_over_virial_radius
total_potential_energy
=
np
.
sum
(
v_c
**
2
*
np
.
log
(
r
))
potential_energy_array
=
np
.
append
(
potential_energy_array
,
total_potential_energy
)
vels_dset
=
f
[
"
PartType0/Velocities
"
]
vels
=
np
.
array
(
vels_dset
)
speed_squared
=
coords
[:,
0
]
**
2
+
coords
[:,
1
]
**
2
+
coords
[:,
2
]
**
2
total_kinetic_energy
=
0.5
*
np
.
sum
(
speed_squared
)
kinetic_energy_array
=
np
.
append
(
kinetic_energy_array
,
total_kinetic_energy
)
u_dset
=
f
[
"
PartType0/InternalEnergy
"
]
u
=
np
.
array
(
u_dset
)
total_internal_energy
=
0.5
*
np
.
sum
(
u
)
internal_energy_array
=
np
.
append
(
internal_energy_array
,
total_internal_energy
)
#put energies in units of v_c^2 and rescale by number of particles
pe
=
potential_energy_array
/
(
N
*
v_c
**
2
)
ke
=
kinetic_energy_array
/
(
N
*
v_c
**
2
)
ie
=
internal_energy_array
/
(
N
*
v_c
**
2
)
te
=
pe
+
ke
+
ie
print
pe
print
ke
print
ie
print
te
dyn_time_cgs
=
r_vir_cgs
/
v_c_cgs
time_array
=
time_array_cgs
/
dyn_time_cgs
plt
.
plot
(
time_array
,
ke
,
label
=
"
Kinetic Energy
"
)
plt
.
plot
(
time_array
,
pe
,
label
=
"
Potential Energy
"
)
plt
.
plot
(
time_array
,
ie
,
label
=
"
Internal Energy
"
)
plt
.
plot
(
time_array
,
te
,
label
=
"
Total Energy
"
)
plt
.
legend
(
loc
=
"
lower right
"
)
plt
.
xlabel
(
r
"
$t / t_{dyn}$
"
)
plt
.
ylabel
(
r
"
$E / v_c^2$
"
)
plt
.
title
(
r
"
$%d \, \, \mathrm{particles} \,,\, v_c = %.1f \, \mathrm{km / s}$
"
%
(
N
,
v_c
))
plt
.
ylim
((
-
2
,
2
))
#plot_filename = "density_profile_%03d.png" %i
plt
.
show
()
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