# AcuProj

Project the solution fields of a solved problem to another mesh.

## Syntax

acuProj [options]

## Type

AcuSolve Preparatory Program

## Description

AcuProj is a simple utility program that projects the solution from the restart files of a solved problem with one mesh to another mesh. The generated files are suitable for inclusion in the NODAL_INITIAL_CONDITION command of the new problem.

In the following, the full name of each option is followed by its abbreviated name and its type. For a general description of option specifications, see Command Line Options and Configuration Files. See below for more individual option details:

help or h (boolean)
If set, the program prints a usage message and exits. The usage message includes all available options, their current values, and the place where each option is set.
problem or pb (string)
The name of the problem is specified via this option. All generated file names start with this name.
coordinates_file or crd (string)
The coordinates file for the new mesh. The file must contain four columns: node number and x, y, z coordinates. If coordinates_file is set to _auto, problem.crd and problem.crd.B are assumed.
from_problem or fpb (string)
The name of the solved problem is specified via this option. If from_problem is set to _auto, the name of the problem option is used.
from_working_directory or fdir (string)
The working directory of the solved problem. If a relative directory address is provided, that is, the directory does not start with an "/", it is considered relative to the from_problem_directory.
from_problem_directory or fpdir (string)
The home directory of the solved problem.
from_run_id or run (integer)
The run number of the solved problem from which the projection is requested. If from_run_id is set to 0, the last eligible run is assumed; see description below for more details.
from_time_step or ts (integer)
The time step of the solved problem from which the projection is requested. If from_time_step is set to 0, the last available time step consistent with from_run_id is assumed; see description below for more details.
search_technique or search (enumerated)
Technique for evaluating the projection:
node
Choose the value of the closest node.
element
Perform element interpolation.
line_buff or lbuff (boolean)
Flush standard output after each line of output.
verbose or v (integer)
Set the verbose level for printing information to the screen. Each higher verbose level prints more information. If verbose is set to 0, or less, only warning and error messages are printed. If verbose is set to 1, basic processing information is printed in addition to warning and error messages. This level is recommended. verbose levels greater than 1 provide information useful only for debugging.

## Examples

Suppose you have a solved channel problem in the problem directory channel1. Assume you have a new mesh in a sister directory channel2. To project the solution from channel1 to channel2, issue the following command from channel2:
acuProj -pb channel -crd channel.crd -fpb channel -fpdir ../channel1
or alternatively place the options in the configuration file Acusim.cnf as
problem                 = channel
coordinates_file        = channel.crd
from_problem            = channel
from_problem_directory  = ../channel1
and invoke AcuProj as
acuProj
The above command takes the latest run which has a restart file and projects its nodal fields to the nodes of the new mesh. If you assume that the channel problem was solved for the flow equation only, then the above command generates the files channel.vel.nic and channel.pres.nic for the nodal velocity and pressure fields, respectively. These files may be included in the new input file via the NODAL_INITIAL_CONDITION command as follows:
NODAL_INITIAL_CONDITION ( velocity ) {
}
NODAL_INITIAL_CONDITION ( pressure ) {
}
The following table lists the nodal fields that AcuProj projects from the restart file, if such fields exist. Also included in the table are the names of the resulting files.
Nodal Field
File Name
velocity
problem.vel.nic
pressure
problem.pres.nic
temperature
problem.temp.nic
species
problem.spec_id.nic
eddy viscosity
problem.eddy.nic
turbulence kinetic energy
problem.tke.nic
turbulence eddy frequency
problem.tomega.nic
viscoelastic stress
problem.vest.nic

For the species field, ID ranges from 1 to the number of species.

The options from_run_id and from_time_step specify the restart run and time step to extract the data. Either or both options may be set to 0, indicating the use of the latest data:

Table 1.
from_run_id from_time_step Approach
>0 >0 Use the restart data from the specified run and time step
0 >0 Use the restart data from highest run that has the specified restart time step
>0 0 Use the restart data from the last time step of the specified run
0 0 Use the restart data from the latest run and time step

Note that the physical domains of the two meshes do not need to match. If a nodal point of the new mesh falls outside the domain of the solved mesh, the values on the boundary node of the solved mesh closest to the node under consideration are used.

Two projection methods are available: node and element. The node search technique assigns the values of the closest node from the solved problem, whereas the element search technique performs an element interpolation. The latter technique is more accurate, but potentially much more expensive.