# RESPONSE VARIABLE

Specifies the responses to be used for optimization.

AcuSolve Command

## Syntax

RESPONSE_VARIABLE {parameters}

## Qualifier

This command has no qualifier.

## Parameters

type (enumerated) [=surface_output]
Responsible variable types.
element_output
time_history_output
time_history_output_distance or dist
design_variable
constant or const
identity or id
square or sq
cube
square_root or sqrt
exponential_function or exp
natural_logarithm or ln
sine or sin
cosine or cos
tangent or tan
cotangent or cot
arcsine or asin
arccosine or acos
arctangent or atan
arccotangent or acot
negation or neg
reciprocal or one_over
absolute or abs
ratio or over
subtraction or minus
multiplication or times
power or pow
average or mean
average_absolute_value
minimum or min
minimum_absolute_value
absolute_minimum_value
maximum or max
maximum_absolute_value
absolute_maxmimum_value
summation or sum
sum_absolute_value
sum_squares
sqrt_sum_squares or norm
weighted_sum
product
surface_output (string) [=""]
User defined name of the surface from which the output will be extracted.
surface_output_variable (enumerated) [=pressure]
The surface output variables are used in the RESPONSE_VARIABLE command.
x_traction
y_traction
z_traction
mass_flux
heat_flux
x_velocity or xvel
y_velocity or yvel
z_velocity or zvel
temperature or temp
pressure or pres
area
partial_volume
element_output (string) [=""]
User defined name of the element set from which the output will be extracted.
element_output_variable (enumerated) [=volume]
Element output quantities are used in optimization.
volume
x_velocity or xvel
y_velocity or yvel
z_velocity or zvel
pressure or pres
temperature or temp
total_pressure
mass
time_history_output (string) [="unknown"]
User defined name of time history output.
time_history_output_variable (enumerated) [=pressure]
Time history output quantities are used in optimization.
x_undeformed or x0
y_undeformed or y0
z_undeformed or z0
x_deformed or x
y_deformed or y
z_deformed or z
x_velocity or xvel
y_velocity or yvel
z_velocity or zvel
pressure or pres
temperature or temp
time_history_output_1 (string) [=" "]
User defined name of time history output point. Used with time_history_output_distance.
time_history_output_2 (string) [=""]
User defined name of time history output point. Used with time_history_output_distance.
time_history_output_coordinates_1 (enumerated) [=deformed]
Specifies the method of tracking time_history_output_1 location.
undeformed_coordinates or undeformed
deformed_coordinates or deformed
time_history_output_coordinates_2 (enumerated) [=deformed]
Specifies the method of tracking time_history_output_2 location.
undeformed_coordinates or undeformed
deformed_coordinates or deformed
time_history_index_1 (integer) [=1]
Time history indices must be referenced by the order of the coordinates in the time history output command.
time_history_index_2 (integer) [=1]
Time history indices must be referenced by the order of the coordinates in the time history output command.
design_variable (string) [=""]
User defined name of the design variable.
constant_response (real) [=0.0]
Specifies a constant value.
response_variables (list) [={}]
Specifies the response variables.
weights (array) [={}]
Specifies the factors multiplying the response variables in a weighted sum. If you use M response variables in the weighted sum, you need to specify M weights.

## Description

The objectives and constraints are defined in terms of response variables that may reference surface or volume outputs. Response variables may also control parameters by using multiplier functions of type set to response_variable. The values of the objective and constraint functions are computed using response variable commands. In turn, the values of the response variable functions are computed from either (i) integrated surface quantities, (ii) integrated volume quantities, (iii) design variables, (iv) given constants, or (v) functions of one or more other response variables.

Below are some examples of responses.

Response variable generated using surface output:
RESPONSE_VARIABLE(“inflow pressure”) {
type                    = surface_output
surface_output          = “inflow”
surface_output_variable = pressure
}
SURFACE_OUTPUT(“inflow”) {
shape                       = three_node_triangle
element_set                 = “fluid”
integrated_output_frequency = 1
}
Response variable generated using element output:
RESPONSE_VARIABLE(“mass of object”) {
type                    = element_output
element_output          = “object”
element_output_variable = mass
}
ELEMENT_OUTPUT(“object”) {
shape                       = four_node_tet
element_set                 = “object”
integrated_output_frequency = 1
}
Response variable generated using time history output:
RESPONSE_VARIABLE(“temperature in a node”) {
type                         = time_history_output
time_history_output          = “oth_node”
time_history_output_variable = temperature
}
TIME_HISTORY_OUTPUT(“oth_node”) {
type             = nodal
nodes            = { 54 }
output_frequency = 1
}
RESPONSE_VARIABLE(“x-position of a deformed point”) {
type                         = time_history_output
time_history_output          = “oth_point”
time_history_output_variable = x_deformed
}
TIME_HISTORY_OUTPUT(“oth_point”) {
type             = coordinates
coordinates      = { 1, 1,0, 0.0, 2.0 }
output_frequency = 1
}
Response variable generated based on time history output distance:
RESPONSE_VARIABLE(“distance between two deformed points”) {
type                              = time_history_output
time_history_output_1             = “points”
time_history_output_2             = “points”
time_history_output_coordinates_1 = deformed
time_history_output_coordinates_2 = deformed
time_history_index_1              = “1”
time_history_index_2              = “2”
}
TIME_HISTORY_OUTPUT(“oth_point”) {
type             = coordinates
coordinates      = {
1, 0.0, 0.0, 0.0
2, 2.0, 3.0, 0.0
}
output_frequency = 1
}

Note that the indices in time history output are numbered from one to two and are referenced in the response variable command. In general, the response variable command time history indices must be referenced by the order of the coordinates in the time history output command. The first column is not the index number, but the point identifier.