Aerodynamic Forces

Attributes

Attributes form the smallest data member of the driver file. Attributes can be real, integer, strings or Booleans (True/False).

[BLOCK_NAME]
ATTRIBUTE_1  = 'TRUE'
ATTRIBUTE_2  = 1.0
ATTRIBUTE_3  = 'Wind_velocity'
ATTRIBUTE_4  = 8

Attribute names are:

• Strings
• Case insensitive, for example: TAG and tag are equivalent.
• In the above example, the attributes are: TAG, SATURATION, LOOK_AHEAD_TIME, DEMAND_FILE, INTEGRATION_STEP_SIZE are the attribute names.

Attribute value:

• Real, integer, string, bool
• Strings should be written in ‘single quotes’ or “double quotes”
• 0, 0.00, N, NO, FALSE, F are all depicted as false
• 1, 1.00, T, TRUE, Y, YES are all depicted as true
• Case sensitive

Format:

ATTRIBUTE_NAME = ATTRIBUTE_VALUE

Block

Blocks form the most versatile data structure of the reader utility. It acts as container for all other data members except a block.

• Block can contain any number of sub-blocks.
• Block cannot contain a block.
• Block can contain multiple tables but only storing them in different sub-blocks.

Format:

[BLOCK_NAME]
ATTRIBUTE(s)
SUBBLOCK(s)
TABLE

Block ends with the end of file or start of new Block.

Sub-block

Sub-blocks are structurally similar to blocks with an only difference that they cannot contain sub blocks or blocks.

• A sub block cannot contain more than one table.

Format:

(SUBBLOCK_NAME)
ATTRIBUTE(s)
TABLE(s)

Table

Data structure which consists of fields (rows and columns).

• Table can contain any type of attributes.
• In no label is provided, the default is to label them as indices starting from 0.

Format:

{LABEL1       LABEL2      LABEL3}
ATTRIBUTE00   ATTRIBUTE01   ATTRIBUTE02
ATTRIBUTE10   ATTRIBUTE11   ATTRIBUTE12
ATTRIBUTE20   ATTRIBUTE21   ATTRIBUTE22

Units

‘Units’ is a special block that conveys the reader units of the property file.

• Every property sheet should necessarily have a units block.
• User defined units in tables.

Comment

Anything written in line after ‘$’ is ignored by the reader utility.

[ENVIRONMENT]
$These are environment conditions for the simulation
GAS_CONSTANT                    	= 287e3
AMBIENT_PRESSURE                	= 0.101325
AMBIENT_TEMPERATURE             	= 298
WIND_VELOCITY		= 'WIND_VELOCITY'

$-----------------------------------------------------------------ALTAIR_HEADER
[ALTAIR_HEADER]
FILE_TYPE 	= 'AAE'
FILE_VERSION 	= 1.0
FILE_FORMAT 	= 'ASCII'
ENTITY_TYPE     	= 'AERODYNAMIC_FORCE'

$---------------------------------------------------------------GEOMETRIC_PROPERTIES
[GEOMETRIC_PROPERTIES]
FRONTAL_SECTION_AREA        = 2e6

$---------------------------------------------------------------ENVIRONMENT
[ENVIRONMENT]
GAS_CONSTANT                    	= 287e3
AMBIENT_PRESSURE                	= 0.101325
AMBIENT_TEMPERATURE             	= 298
WIND_VELOCITY		= 'WIND_VEL_1'
$Wind vel is with respect to global frame
$---------------------------------------------------------------WIND_VELOCITY
[WIND_VEL_1]
$Wind vel is with respect to global frame
VX                    = 1000
VY                    = 0
VZ                    = 0  

$---------------------------------------------------------------DRAG_COEFFICIENT
[DRAG_COEFFICIENT]
INTERPOLATION = 'AKIMA'
(SPLINE_DATA)
{INCIDENCE_ANGLE    COEFFICIENT}
0.0                 0.3
10.0                0.31
20.0                0.32
30.0                0.33

$--------------------------------------------------------------- SIDEFORCE_COEFFICIENT	
[SIDEFORCE_COEFFICIENT]
INTERPOLATION = 'AKIMA'
(SPLINE_DATA)
{INCIDENCE_ANGLE    COEFFICIENT}
0.0                 0.3
10.0                0.31
20.0                0.32
30.0                0.33

$--------------------------------------------------------------- LIFT_COEFFICIENT_FRONT
[LIFT_COEFFICIENT_FRONT]
INTERPOLATION = 'AKIMA'
(SPLINE_DATA)
{INCIDENCE_ANGLE    COEFFICIENT}
0.0                 0.3
10.0                0.31
20.0                0.32
30.0                0.33

$--------------------------------------------------------------- LIFT_COEFFICIENT_REAR
[LIFT_COEFFICIENT_REAR]
INTERPOLATION = 'AKIMA'
(SPLINE_DATA)
{INCIDENCE_ANGLE    COEFFICIENT}
0.0                 0.3
10.0                0.31
20.0                0.32
30.0                0.33

$--------------------------------------------------------------- ROLL_COEFFICIENT
[ROLL_COEFFICIENT]
INTERPOLATION = 'AKIMA'
(SPLINE_DATA)
{INCIDENCE_ANGLE    COEFFICIENT}
0.0                 0.3
10.0                0.31
20.0                0.32
30.0                0.33

This section contains the data related to vehicle geometry. Calculation of the aerodynamic forces require the frontal area of the vehicle which is specified in this block.

$--------------------------------------------------------------- YAW_COEFFICIENT [YAW_COEFFICIENT]
INTERPOLATION = 'AKIMA'
(SPLINE_DATA)
{INCIDENCE_ANGLE    COEFFICIENT}
0.0                 0.3
10.0                0.31
20.0                0.32
30.0                0.33

1. Start MotionView from the installation folder of HyperWorks.
   The MotionView window is displayed.

   
   
   Figure 3.

2. Click Model > Assembly Wizard.

   
   
   Figure 4.

   The Car/Small truck - Model Type dialog opens.

1. Select the Full vehicle with driver option from the Model Type dialog and click Next.

   
   
   Figure 5.

2. Select the Aerodynamic Forces on the additional systems page and complete the model selection.

   
   
   Figure 6.

   Note: Aerodynamic Forces is now included as a system.
3. The Full vehicle with driver model including the aerodynamic forces system build through the Assembly Wizard is displayed in the graphics area.

   
   
   Figure 7.

4. The subsystems with the Aerodynamic Forces you have selected in the Assembly Wizard to build the model are displayed in the browser.

   
   
   Figure 8.