/IMPL/DT/2

Engine Keyword Implicit automatic time step control method 2.

Format

/IMPL/DT/2

lt_w L_arc L_dtn Δ T s c a _ d MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeiLdiaads fadaWgaaWcbaGaam4CaiaadogacaWGHbGaai4xaiaadsgaaeqaaaaa @3CA7@ Δ T s c a _ max MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeiLdiaads fadaWgaaWcbaGaam4CaiaadogacaWGHbGaai4xaiaadsgaaeqaaaaa @3CA7@

Definitions

Data Description SI Unit Example
It_w If the solution of a time step converges within It_w iterations, the next time step will be increased by a factor controlled by Δ Tsca_max.
= 0
Set to 6
  
L_arc Input arc-length.
= 0
Will be calculated automatically.
  
L_dtn Maximum number of iterations before resetting and decreasing the time step by a factor of Δ T s c a _ d MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeiLdiaads fadaWgaaWcbaGaam4CaiaadogacaWGHbGaai4xaiaadsgaaeqaaaaa @3CA7@ .
= 0
Set to 20
  
Δ T s c a _ d MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeiLdiaads fadaWgaaWcbaGaam4CaiaadogacaWGHbGaai4xaiaadsgaaeqaaaaa @3CA7@ Scale factor for decreasing the time step, if L_dtn is reached.
= 0
Set to 0.67
  
Δ T s c a _ max MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeiLdiaads fadaWgaaWcbaGaam4CaiaadogacaWGHbGaai4xaiaadsgaaeqaaaaa @3CA7@ Maximum scale factor for increasing the time step.
= 0
Set to 1.1
  

Comments

  1. Arc-length method is used to accelerate and to control the convergence. The time step is determined by displacement norm control (arc-length).
  2. This method is preferred for general nonlinear implicit analysis.
  3. If /IMPL/DT/1, /IMPL/DT/2, or /IMPL/DT/3 are not present, the only time step controls are /IMPL/NCYCLE/STOP and /IMPL/DT/STOP. In the case of divergence, the time step will be reduced by half and repeated.