It is recommended that the user refer to the CFL3D Tutorial page for additional information on unsteady aeroelasticity capabilities.

__CONTENTS__

** Acknowledgment:** Thanks to Peter Hartwich of Boeing Phantom
Works, Long Beach, for suggesting and providing the model routines for
coupling the CAPTSD structural solver with CFL3D.

__SAMPLE INPUT AND PARAMETER DEFINITIONS__

**Notes:**- Aeroelastic analysis can only be utilized in time-accurate mode, i.e.
**dt > 0** - The mesh movement flag,
**iunst**, must be set equal to 2. - If iunst=2, the following lines in the input file must appear
the control surface data section (line types LT31 through LT32 in the terminology of the Version 5 User Manual) in order to enable the aeroelastic option:*after*

- Aeroelastic analysis can only be utilized in time-accurate mode, i.e.
**Example: Single-zone, 2D grid with one aeroelastic surface:**moving grid data - deforming surface (forced motion) ndefrm 0 lref grid idefrm rfreqi omegax omegay omegaz xorig yorig zorig grid icsi icsf jcsi jcsf kcsi kcsf moving grid data - aeroelastic surface (aeroelastic motion) naesrf 1 iaesrf ngrid grefl uinf qinf nmodes iskyhk 1 -1 1.333333 393. 155. 2 0 freq gmass damp x0(2*n-1) x0(2*n) gf0(2*n) 21.363 1. 0. 0. 0. 0. 32.421 1. 0. 0. 0. 0. moddfl amp freq t0 0 0. 0. 0. 0 0. 0. 0. grid iaei iaef jaei jaef kaei kaef 1 0 0 0 0 0 0 moving grid data - skip data for field/multiblock mesh movement nskip isktyp beta1 alpha1 beta2 alpha2 nsprgit 0 -1 1.0 1.0 1.0 0.05 0 grid iskip jskip kskip

In all deforming mesh applications, the additional input is broken up into three sections, as illustrated in the example above: 1) forced motion, 2) aeroelastic motion, and moving grid data.

For any problem in which the forced motion is not used, but the aeroelastic response of one or more surfaces is desired (which is the focus of this section), the forced-motion input section should appear as shown above - the only numerical value which should appear is the value of ndefrm, the number of surfaces undergoing forced motion - zero.

The following definitions apply for the aeroelastic section:

**naesrf**- number of aeroelastic surfaces; each aeroelastic surface is represented as a distinct set of modal shapes. Most typically, naesrf = 1, but for example, naesrf = 2 would allow the wing to be represented with one set of mode shapes, while the tail could be represented with a different set of mode shapes. All of the remaining data is repeated as a block for each of the aeroelastic surfaces from 1 to naesrf.
**iaesrf**- the aeroelastic surface for which the data is being set
**ngrid**- the number of grids which contain the aeroelastic surface
**iaesrf**. If**ngrid = -1**, then the aeroelastic surface is assumed to be comprised of all solid surfaces (i.e. bc types 1005, 1006 or 2004) within the entire grid system. Thus,**ngrid = -1**is appropriate only for**naesrf = 1**. **grefl**- the reference length, in grid units, used to nondimensionalize the reduced frequency associated with the mode shapes of the aeroelastic surface.
**uinf**- reference flow speed used to nondimensionalize the reduced frequency.
**qinf**- reference dynamic pressure used to nondimensionalize the gneralized forces.
**nmodes**- number of modes used to represent the aeroelastic surface.
**iskyhk**- flag to indicate the use of the "skyhook" terms.
**NOT YET IMPLEMENTED**. However, a value must still be input as a placeholder (any value will do).

The lines following

**freq gmass ... gf0**are repeated**nmodes**times, with data arranged from mode 1 to mode**nmode**:**freq**- the wind-off natural freqency of the mode.
**gmass**- the generalized mass to include for the mode.
**damp**- the damping factor of the mode
**x0(2*n-1)**- the initial generalized displacement of the mode; if non-zero, will overide the value in the restart file (if restarting). this allows the mode to be perturbed for dynamic response studies
**x0(2*n)**- the initial generalized velocity of the mode; if non-zero, will overide the value in the restart file (if restarting). this allows the mode to be perturbed for dynamic response studies
**gf0(2*n)**- the generalized force to include for the mode.

The lines following

**moddfl amp ... t0**are repeated**nmodes**times, with data arranged from mode 1 to mode**nmode**:**moddfl**- type of time-varying modal perturbation desired:
- = 0, no perturbation
- = 1, harmonic (sinusoidal) perturbation
- = 2, Gassian pulse
- = 3, step pulse
**amp**- amplitude of modal perturbation. use any value as a placeholder if
**moddfl = 0** **freq**- reduced frequncy of modal perturbation if
**moddfl = 1** - half-width of Gaussian pulse if
**moddfl = 2** - use any value as a placeholder for
**moddfl = 0 or 4** **t0**- time about which Gaussian pulse is centered if
**moddfl = 2** - time at which step pulse starts is centered if
**moddfl = 3** - use any value as a placeholder for
**moddfl = 0, 1, or 4**

The lines following

**grid iaei ... kaef**are repeated**|ngrid|**times:**grid**- grid containing all or part of the current aeroelastic surface
**iaesrf**. use any value as a placeholder if**ngrid = -1**. **iaei**- starting i-index of the current aeroelastic surface in zone
**grid**. use any value as a placeholder if**ngrid = -1**. **iaef**- ending i-index of the current aeroelastic surface in zone
**grid**. use any value as a placeholder if**ngrid = -1**. **jaei**- starting j-index of the current aeroelastic surface in zone
**grid**. use any value as a placeholder if**ngrid = -1**. **jaef**- ending j-index of the current aeroelastic surface in zone
**grid**. use any value as a placeholder if**ngrid = -1**. **kaei**- starting k-index of the current aeroelastic surface in zone
**grid**. use any value as a placeholder if**ngrid = -1**. **kaef**- ending k-index of the current aeroelastic surface in zone
**grid**. use any value as a placeholder if**ngrid = -1**.

**Responsible NASA Official:**
Christopher Rumsey

**Page Curator:**
Christopher Rumsey

**Last Updated:** 03/29/2013