Impose Regions Definitions
nanoFluidX has the capability to define an arbitrary number of regions, which fall into one of the three categories (types): fluid velocity, body force, and temperature.
The fluid velocity region can be specified in a rectangular or spherical shape and it hard-imposes a velocity on all fluid particles which are within the prescribed region. The easiest analogy is a pump mechanism (momentum source), except that there are no moving parts involved. The body force region imposes a defined body force on all the particles which are within the defined region. It also can be thought of as a momentum source region, except that by defining the body force instead of hard-setting the velocity of the particles, the region is likely to behave more stably. Finally, the temperature region assigns a temperature to all fluid or wall particles (optional) which are within the prescribed region, and is essentially a heat source/sink.
imposeRegions
{
imposeRegion
{
imposeRegion_type \CUBOIDVEL
cuboidvel_unv "1. 2. 0."
cuboidvel_vel 1.
cuboidvel_min "0. 0. 0."
cuboidvel_max "0.4 0.4 0.4"
t_start 0.
t_end 10.
t_damping 0.1
cuboidvel_tvs_file time_velocity_series.txt
cuboidvel_tvs_offset 0.1
cuboidvel_tvs_latch false
}
imposeRegion
{
imposeRegion_type CYLINDERVEL
cylindervel_unv "1. 2. 0."
cylindervel_vel -0.4
cylindervel_rad 0.1
cylindervel_pbl true
;[option 1]
cylindervel_cntr "-0.4 0. 0."
cylindervel_hght 0.02
;[option 2]
cylindervel_pnt1 "-0.4 0. 0."
cylindervel_pnt2 "-0.4 0. 0."
t_start 0.
t_end 10.
t_damping 0.1
cylindervel_tvs_file time_velocity_series.txt
cylindervel_tvs_offset 0.1
cylindervel_tvs_latch false
}
imposeRegion
{
imposeRegion_type SPHEREVEL
spherevel_unv "1. 2. 0."
spherevel_vel -1.
spherevel_cntr "-0.4 0. 0."
spherevel_rad 0.02
t_start 0.
t_end 10.
t_damping 0.1
spherevel_tvs_file time_velocity_series.txt
spherevel_tvs_offset 0.1
spherevel_tvs_latch false
}
imposeRegion
{
imposeRegion_type CUBOIDACC
cuboidacc_acc "1. 0. 0."
cuboidacc_min "0. 0. 0."
cuboidacc_max "0.4 0.4 0.4"
t_start 0.
t_end 10.
t_damping 0.1
}
imposeRegion
{
imposeRegion_type CUBOIDTEMP
cuboidtemp_temp "1. 0. 0."
cuboidtemp_fluidonly false
cuboidtemp_min "0. 0. 0."
cuboidtemp_max "0.4 0.4 0.4"
t_start 0.
t_end 10.
t_damping 0.1
}
...
}
- t_start / t_end
- Common parameters for all imposed regions, indicating beginning and end of time at which the region is active.
- t_damping
- During this period, the prescribed velocity, body force or temperature will reach it prescribed value (analogous to the t_damping in the Imposed Motions section).
- imposeRegion_type
- Defines the type of the imposed region.
- cylindervel_unv, cuboidvel_unv, spherevel_unv
- Defines the velocity normal vector within an imposed velocity region. This determines the direction of the velocity vector.
- cylindervel_vel, cuboidvel_vel, spherevel_vel
- Defines the velocity magnitude within an imposed velocity region.
- cuboidvel_min, cuboidacc_min, cuboidtemp_min
- Minimum bounds of the rectangular impose region box.
- cuboidvel_max, cuboidacc_max, cuboidtemp_max
- Maximum bounds of the rectangular impose region box.
- cylindervel_rad
- Cylinder radius.
- cylindervel_pbl
- Boolean switch that enables a parabolic velocity profile when cylindrical imposed velocity regions are used.
- Use a direction vector, starting point, and cylinder height to define a cylinder.
- Use two points, where point 1 is the starting point and point 2 is the ending point (thus defining the direction of the cylinder).
- cylindervel_cntr
- Coordinates of the base point of the cylinder.
- cylindervel_hght
- Height of the cylinder (distance between two bases).
- cylindervel_pnt1
- Coordinates of the base point of the cylinder.
- cylindervel_pnt2
- Coordinates of the top point of the cylinder.
- spherevel_cntr
- Location of the spherical velocity impose region.
- spherevel_rad
- Radius of the spherical velocity impose region.
- cuboidtemp_temp
- Temperature which will be assigned to all the particles which enter the rectangular temperature region.
- cuboidtemp_fluidonly
- Switch which allows to prescribe the temperature to only fluids, or alternatively to all FLUID, MOVINGWALL or WALL particles.
- cuboidvel_tvs_file, cylindervel_tvs_file, spherevel_tvs_file
- Variable prescribed velocity file (Time Velocity Series – TVS).
- cuboidvel_tvs_offset, cylindervel_tvs_ offset, spherevel_tvs_ offset
- Time offset value in case that the TVS file starts at a time different from zero (e.g. begin using TVS at t = 10 s).
- cuboidvel_tvs_latch, cylindervel_tvs_latch, spherevel_tvs_latch
- Boolean command for keeping the last value of the TVS file throughout the simulation.