AdjustTimeStep Custom Task - Revision history

Nairnj: /* Introduction */

2024-09-03T23:41:18Z

Introduction

← Older revision		Revision as of 23:41, 3 September 2024
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	For convergence of explicit, dynamic calculations, like [[NairnMPM]], the time step must be less then the time it takes a stress wave or a particle at its current velocity to pass across the smallest element size. For safety, the time step is usually calculated to be some fraction of this time as specified by the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy factor (C)]]. But, for some [[Material Models\|material types]], the wave speed might change during the calculations thereby necessitating an adjustment in the time step to retain convergence. This tasks allows you to periodically adjust the time step.		For convergence of explicit, dynamic calculations, like [[NairnMPM]], the time step must be less then the time it takes a stress wave or a particle at its current velocity to pass across the smallest element size. For safety, the time step is usually calculated to be some fraction of this time as specified by the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy factor (C)]]. But, for some [[Material Models\|material types]], the wave speed might change during the calculations thereby necessitating an adjustment in the time step to retain convergence. This tasks allows you to periodically adjust the time step.

	When activated, this task looks at each particle and finds the current wave speed, c<sub>s</sub>, and ~~an effective~~ particle speed		When activated, this task looks at each particle and finds the current wave speed, c<sub>s</sub>, and particle speed


	<math>c_p = \|v_x\| + \|v_y\| + \|v_z\|</math>		<math>c_p = \sqrt{v_x^2+v_y^2+v_z^2}</math>

	The time step is then set to minimum time (over all particles, p) for the particle to cross minimum cell size (Δx) at the two speeds (c<sub>s</sub> and c<sub>p</sub>):		The time step is then set to minimum time (over all particles, p) for the particle to cross minimum cell size (Δx) at the two speeds (c<sub>s</sub> and c<sub>p</sub>):

Nairnj: /* Material Support */

2021-01-02T19:02:13Z

Material Support

← Older revision		Revision as of 19:02, 2 January 2021
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	* [[Viscoelastic Material\|Viscoelastic]]		* [[Viscoelastic Material\|Viscoelastic]]

	All other materials have wave speed that is independent of particle state (or ~~not calculation is~~ implement to ~~evalate~~ particle-state effects). ~~They~~ will still adjust time step, however, if particles approach the wave speed of the material. These adjustments can help highly-dynamic simulations.		All other materials have wave speed that is independent of particle state (or no calculations are implement to evaluate particle-state effects). These materials will still adjust time step, however, if particles approach the wave speed of the material. These adjustments can help highly-dynamic simulations.

Nairnj: /* Material Support */

2021-01-02T19:01:11Z

Material Support

← Older revision		Revision as of 19:01, 2 January 2021
Line 47:		Line 47:
	This custom task can be used with any material and respond to material point velocities. But, it should also look at current wave speed in materials, especially when compressed. This task only accounts for pressure dependent properties if some particles are using [[Material Models\|material classes]] for which the wave speed changes with particle state and for which the material class coding responds to <tt>CurrentWaveSpeed()</tt> to provide that state-dependent wave speed. The [[Material Models\|material classes]] that current provide this support are:		This custom task can be used with any material and respond to material point velocities. But, it should also look at current wave speed in materials, especially when compressed. This task only accounts for pressure dependent properties if some particles are using [[Material Models\|material classes]] for which the wave speed changes with particle state and for which the material class coding responds to <tt>CurrentWaveSpeed()</tt> to provide that state-dependent wave speed. The [[Material Models\|material classes]] that current provide this support are:

			* [[Clamped Neo-Hookean Material\|ClampedNeohookean]]
			* [[Isotropic, Hyperelastic-Plastic Material\|HEIsotropic]]
	* [[Isotropic, Hyperelastic-Plastic Mie-Grüneisen Material\|HEMGEOSMaterial]]		* [[Isotropic, Hyperelastic-Plastic Mie-Grüneisen Material\|HEMGEOSMaterial]]
	* [[Ideal Gas Material\|IdealGas]]		* [[Ideal Gas Material\|IdealGas]]
			* [[Mooney Material\|Mooney]]
			* [[Mooney Membrane Material\|MooneyMembrane]]
			* [[Neo-Hookean Material\|Neohookean]]
			* [[First Order Phase Transition Material\|PhaseTransition]]
			* [[ReactionPhase]]
	* [[Tait Liquid Material\|TaitLiquid]]		* [[Tait Liquid Material\|TaitLiquid]]
	* [[Clamped Neo-Hookean Material\|ClampedNeohookean]]
	* [[Viscoelastic Material\|Viscoelastic]]		* [[Viscoelastic Material\|Viscoelastic]]
	* [[Mooney Material\|Mooney]]
	* [[Neo-Hookean Material\|Neohookean]]

	Some other [[Material Models\|material classes]] could have wave speed that depends on particle state, but do not yet provide the needed <tt>CurrentWaveSpeed()</tt> code. These materials, which will update in the future as needed, are:

	* [[Isotropic, Hyperelastic-Plastic Material\|HEIsotropic]]
	* [[Isotropic, Elastic-Plastic Material\|IsoPlasticity]]
	* [[Anisotropic, Elastic-Plastic Material\|HillPlastic]]
	* [[Anisotropic, Hyperelastic Material\|HEAnisotropic]]

	All other materials have wave speed that is independent of particle state ~~and therefore~~ will ~~only have dynamic adjustment of the~~ time step ~~on conditions where~~ particles ~~are approaching~~ the ~~initial~~ wave speed of the material.		All other materials have wave speed that is independent of particle state (or not calculation is implement to evalate particle-state effects). They will still adjust time step, however, if particles approach the wave speed of the material. These adjustments can help highly-dynamic simulations.

Nairnj: /* Task Scheduling */

2021-01-02T18:44:33Z

Task Scheduling

← Older revision		Revision as of 18:44, 2 January 2021
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	* <tt>(verbose)</tt> - If value is greater than 0.99, it will print the new time step whenever it changes by a factor equal to value of <tt>(verbose)</tt>. For backward compatibility, if entered value is 1, the report factor will set to 2 fold change in time step. If value is less than 0.99, the new time step is silently changed. The default it 0.		* <tt>(verbose)</tt> - If value is greater than 0.99, it will print the new time step whenever it changes by a factor equal to value of <tt>(verbose)</tt>. For backward compatibility, if entered value is 1, the report factor will set to 2 fold change in time step. If value is less than 0.99, the new time step is silently changed. The default it 0.
	* <tt>(Cvel)</tt> - Enter a different Courant–Friedrichs–Lewy factor to use for particle velocities. This parameter is optional. The default is for <tt>(Cvel)</tt> to be the same as the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy (C)]].		* <tt>(Cvel)</tt> - Enter a different Courant–Friedrichs–Lewy factor to use for particle velocities. This parameter is optional. The default is for <tt>(Cvel)</tt> to be the same as the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy (C)]].
	* <tt>(maxInc)</tt> - This option limits any increases in time step to be <tt>(1+(maxInc))*</tt>Δ''t'' where Δ''t'' is the current time step. It is most-commonly needed when using the [[MPM Methods and Simulation Timing#Restarting Time Steps\|time-step restarting option]] because otherwise this task would ~~immediatedly~~ return the time step to its previous value. If not entered, no limits are placed on time step increases.		* <tt>(maxInc)</tt> - This option limits any increases in time step to be <tt>(1+(maxInc))*</tt>Δ''t'' where Δ''t'' is the current time step. It is most-commonly needed when using the [[MPM Methods and Simulation Timing#Restarting Time Steps\|time-step restarting option]] because otherwise this task would immediately return the time step to its previous value. If not entered, no limits are placed on time step increases.

	== Material Support ==		== Material Support ==

Nairnj: /* Task Scheduling */

2021-01-02T18:43:48Z

Task Scheduling

← Older revision		Revision as of 18:43, 2 January 2021
Line 41:		Line 41:
	* <tt>(verbose)</tt> - If value is greater than 0.99, it will print the new time step whenever it changes by a factor equal to value of <tt>(verbose)</tt>. For backward compatibility, if entered value is 1, the report factor will set to 2 fold change in time step. If value is less than 0.99, the new time step is silently changed. The default it 0.		* <tt>(verbose)</tt> - If value is greater than 0.99, it will print the new time step whenever it changes by a factor equal to value of <tt>(verbose)</tt>. For backward compatibility, if entered value is 1, the report factor will set to 2 fold change in time step. If value is less than 0.99, the new time step is silently changed. The default it 0.
	* <tt>(Cvel)</tt> - Enter a different Courant–Friedrichs–Lewy factor to use for particle velocities. This parameter is optional. The default is for <tt>(Cvel)</tt> to be the same as the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy (C)]].		* <tt>(Cvel)</tt> - Enter a different Courant–Friedrichs–Lewy factor to use for particle velocities. This parameter is optional. The default is for <tt>(Cvel)</tt> to be the same as the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy (C)]].
	* <tt>(maxInc)</tt> - This option limits any increases in time step to be <tt>(1+(maxInc))*Δ''t'' where Δ''t'' is the current time step. It is most-commonly needed when using the [[MPM Methods and Simulation Timing#Restarting Time Steps\|time-step restarting option]] because otherwise this task would immediatedly return the time step to its previous value. If not entered, no limits are placed on time step increases.		* <tt>(maxInc)</tt> - This option limits any increases in time step to be <tt>(1+(maxInc))*</tt>Δ''t'' where Δ''t'' is the current time step. It is most-commonly needed when using the [[MPM Methods and Simulation Timing#Restarting Time Steps\|time-step restarting option]] because otherwise this task would immediatedly return the time step to its previous value. If not entered, no limits are placed on time step increases.

	== Material Support ==		== Material Support ==

Nairnj: /* Task Scheduling */

2021-01-02T18:43:23Z

Task Scheduling

← Older revision		Revision as of 18:43, 2 January 2021
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	Parameter verbose,(verbose)		Parameter verbose,(verbose)
	Parameter velocityCFL,(Cvel)		Parameter velocityCFL,(Cvel)
			Parameter maxIncrease,(maxInc)

	In <tt>XML</tt> files, this task is scheduled using a <tt><Schedule></tt> element, which must be within the single <tt><CustomTasks></tt> block:		In <tt>XML</tt> files, this task is scheduled using a <tt><Schedule></tt> element, which must be within the single <tt><CustomTasks></tt> block:
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	<Parameter name='verbose'>(verbose)</Parameter>		<Parameter name='verbose'>(verbose)</Parameter>
	<Parameter name='velocityCFL'>(Cvel)</Parameter>		<Parameter name='velocityCFL'>(Cvel)</Parameter>
			<Parameter name='maxIncrease'>(maxInc)</Parameter>
	</Schedule>		</Schedule>

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	* <tt>(verbose)</tt> - If value is greater than 0.99, it will print the new time step whenever it changes by a factor equal to value of <tt>(verbose)</tt>. For backward compatibility, if entered value is 1, the report factor will set to 2 fold change in time step. If value is less than 0.99, the new time step is silently changed. The default it 0.		* <tt>(verbose)</tt> - If value is greater than 0.99, it will print the new time step whenever it changes by a factor equal to value of <tt>(verbose)</tt>. For backward compatibility, if entered value is 1, the report factor will set to 2 fold change in time step. If value is less than 0.99, the new time step is silently changed. The default it 0.
	* <tt>(Cvel)</tt> - Enter a different Courant–Friedrichs–Lewy factor to use for particle velocities. This parameter is optional. The default is for <tt>(Cvel)</tt> to be the same as the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy (C)]].		* <tt>(Cvel)</tt> - Enter a different Courant–Friedrichs–Lewy factor to use for particle velocities. This parameter is optional. The default is for <tt>(Cvel)</tt> to be the same as the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy (C)]].
			* <tt>(maxInc)</tt> - This option limits any increases in time step to be <tt>(1+(maxInc))*Δ''t'' where Δ''t'' is the current time step. It is most-commonly needed when using the [[MPM Methods and Simulation Timing#Restarting Time Steps\|time-step restarting option]] because otherwise this task would immediatedly return the time step to its previous value. If not entered, no limits are placed on time step increases.

	== Material Support ==		== Material Support ==

Nairnj: /* Task Scheduling */

2017-12-06T22:24:14Z

Task Scheduling

← Older revision		Revision as of 22:24, 6 December 2017
Line 37:		Line 37:

	* <tt>(time)</tt> - Enter the time interval for checking the time step and adjusting it if needed (in [[ConsistentUnits Command#Legacy and Consistent Units\|alt time units]]). This parameter is optional; if it is omitted, the time step adjustment is done each time particle data are archived. To check on every time step enter zero (or any number less than the shortest possible time step).		* <tt>(time)</tt> - Enter the time interval for checking the time step and adjusting it if needed (in [[ConsistentUnits Command#Legacy and Consistent Units\|alt time units]]). This parameter is optional; if it is omitted, the time step adjustment is done each time particle data are archived. To check on every time step enter zero (or any number less than the shortest possible time step).
	* <tt>(verbose)</tt> -If value is greater than 0.99, it will print the new time step whenever it changes by a factor equal to value of <tt>(verbose)</tt>. For backward compatibility, if ~~enter~~ value is 1, the report factor will set to 2 fold change in time step. If value is less than 0.99, the new time step is silently changed. The default it 0.		* <tt>(verbose)</tt> - If value is greater than 0.99, it will print the new time step whenever it changes by a factor equal to value of <tt>(verbose)</tt>. For backward compatibility, if entered value is 1, the report factor will set to 2 fold change in time step. If value is less than 0.99, the new time step is silently changed. The default it 0.
	* <tt>(Cvel)</tt> - Enter a different Courant–Friedrichs–Lewy factor to use for particle velocities. This parameter is optional. The default is for <tt>(Cvel)</tt> to be the same as the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy (C)]].		* <tt>(Cvel)</tt> - Enter a different Courant–Friedrichs–Lewy factor to use for particle velocities. This parameter is optional. The default is for <tt>(Cvel)</tt> to be the same as the input [[MPM Methods and Simulation Timing#Theory: MPM Time Step\|Courant–Friedrichs–Lewy (C)]].

Nairnj: /* Introduction */

2017-11-02T16:51:33Z

Introduction

← Older revision		Revision as of 16:51, 2 November 2017
Line 10:		Line 10:
	<math>c_p = \|v_x\| + \|v_y\| + \|v_z\|</math>		<math>c_p = \|v_x\| + \|v_y\| + \|v_z\|</math>

	The time step is then set to minimum time (over all particles, p) for the particle to cross minimum cell size (Δx) at ~~the maximum of~~ the two speeds (c<sub>s</sub> and c<sub>p</sub>):		The time step is then set to minimum time (over all particles, p) for the particle to cross minimum cell size (Δx) at the two speeds (c<sub>s</sub> and c<sub>p</sub>):

Nairnj: /* Introduction */

2017-11-02T16:50:16Z

Introduction

← Older revision		Revision as of 16:50, 2 November 2017
Line 13:		Line 13:


	<math>\Delta t = \min_p \left({C \Delta x\over c_s} + {C_{vel} \Delta x\over c_p}\right)</math>		<math>\Delta t = \min_p \left({C \Delta x\over c_s}, {C_{vel} \Delta x\over c_p}\right)</math>

	where <math>C_{vel}</math> is an optional different time factor for particle velocities. The time step may go up or down, depending on the states of the particles.		where <math>C_{vel}</math> is an optional different time factor for particle velocities. The time step may go up or down, depending on the states of the particles.

Nairnj: /* Material Support */

2017-10-06T22:47:35Z

Material Support

← Older revision		Revision as of 22:47, 6 October 2017
Line 49:		Line 49:
	* [[Clamped Neo-Hookean Material\|ClampedNeohookean]]		* [[Clamped Neo-Hookean Material\|ClampedNeohookean]]
	* [[Viscoelastic Material\|Viscoelastic]]		* [[Viscoelastic Material\|Viscoelastic]]
			* [[Mooney Material\|Mooney]]
			* [[Neo-Hookean Material\|Neohookean]]

	Some other [[Material Models\|material classes]] could have wave speed that depends on particle state, but do not yet provide the needed <tt>CurrentWaveSpeed()</tt> code. These materials, which will update in the future as needed, are:		Some other [[Material Models\|material classes]] could have wave speed that depends on particle state, but do not yet provide the needed <tt>CurrentWaveSpeed()</tt> code. These materials, which will update in the future as needed, are:

			* [[Isotropic, Hyperelastic-Plastic Material\|HEIsotropic]]
	* [[Isotropic, Elastic-Plastic Material\|IsoPlasticity]]		* [[Isotropic, Elastic-Plastic Material\|IsoPlasticity]]
	* [[Anisotropic, Elastic-Plastic Material\|HillPlastic]]		* [[Anisotropic, Elastic-Plastic Material\|HillPlastic]]
	* [[Mooney Material\|Mooney]]
	* [[Isotropic, Hyperelastic-Plastic Material\|HEIsotropic]]
	* [[Anisotropic, Hyperelastic Material\|HEAnisotropic]]		* [[Anisotropic, Hyperelastic Material\|HEAnisotropic]]

	All other materials have wave speed that is independent of particle state and therefore will only have dynamic adjustment of the time step on conditions where particles are approaching the initial wave speed of the material.		All other materials have wave speed that is independent of particle state and therefore will only have dynamic adjustment of the time step on conditions where particles are approaching the initial wave speed of the material.

← Older revision		Revision as of 19:01, 2 January 2021
Line 47:		Line 47:
	This custom task can be used with any material and respond to material point velocities. But, it should also look at current wave speed in materials, especially when compressed. This task only accounts for pressure dependent properties if some particles are using [[Material Models\|material classes]] for which the wave speed changes with particle state and for which the material class coding responds to <tt>CurrentWaveSpeed()</tt> to provide that state-dependent wave speed. The [[Material Models\|material classes]] that current provide this support are:		This custom task can be used with any material and respond to material point velocities. But, it should also look at current wave speed in materials, especially when compressed. This task only accounts for pressure dependent properties if some particles are using [[Material Models\|material classes]] for which the wave speed changes with particle state and for which the material class coding responds to <tt>CurrentWaveSpeed()</tt> to provide that state-dependent wave speed. The [[Material Models\|material classes]] that current provide this support are:

			* [[Clamped Neo-Hookean Material\|ClampedNeohookean]]
			* [[Isotropic, Hyperelastic-Plastic Material\|HEIsotropic]]
	* [[Isotropic, Hyperelastic-Plastic Mie-Grüneisen Material\|HEMGEOSMaterial]]		* [[Isotropic, Hyperelastic-Plastic Mie-Grüneisen Material\|HEMGEOSMaterial]]
	* [[Ideal Gas Material\|IdealGas]]		* [[Ideal Gas Material\|IdealGas]]
			* [[Mooney Material\|Mooney]]
			* [[Mooney Membrane Material\|MooneyMembrane]]
			* [[Neo-Hookean Material\|Neohookean]]
			* [[First Order Phase Transition Material\|PhaseTransition]]
			* [[ReactionPhase]]
	* [[Tait Liquid Material\|TaitLiquid]]		* [[Tait Liquid Material\|TaitLiquid]]
	* [[Clamped Neo-Hookean Material\|ClampedNeohookean]]
	* [[Viscoelastic Material\|Viscoelastic]]		* [[Viscoelastic Material\|Viscoelastic]]
	* [[Mooney Material\|Mooney]]
	* [[Neo-Hookean Material\|Neohookean]]

	Some other [[Material Models\|material classes]] could have wave speed that depends on particle state, but do not yet provide the needed <tt>CurrentWaveSpeed()</tt> code. These materials, which will update in the future as needed, are:

	* [[Isotropic, Hyperelastic-Plastic Material\|HEIsotropic]]
	* [[Isotropic, Elastic-Plastic Material\|IsoPlasticity]]
	* [[Anisotropic, Elastic-Plastic Material\|HillPlastic]]
	* [[Anisotropic, Hyperelastic Material\|HEAnisotropic]]

	All other materials have wave speed that is independent of particle state ~~and therefore~~ will ~~only have dynamic adjustment of the~~ time step ~~on conditions where~~ particles ~~are approaching~~ the ~~initial~~ wave speed of the material.		All other materials have wave speed that is independent of particle state (or not calculation is implement to evalate particle-state effects). They will still adjust time step, however, if particles approach the wave speed of the material. These adjustments can help highly-dynamic simulations.

← Older revision		Revision as of 22:47, 6 October 2017
Line 49:		Line 49:
	* [[Clamped Neo-Hookean Material\|ClampedNeohookean]]		* [[Clamped Neo-Hookean Material\|ClampedNeohookean]]
	* [[Viscoelastic Material\|Viscoelastic]]		* [[Viscoelastic Material\|Viscoelastic]]
			* [[Mooney Material\|Mooney]]
			* [[Neo-Hookean Material\|Neohookean]]

	Some other [[Material Models\|material classes]] could have wave speed that depends on particle state, but do not yet provide the needed <tt>CurrentWaveSpeed()</tt> code. These materials, which will update in the future as needed, are:		Some other [[Material Models\|material classes]] could have wave speed that depends on particle state, but do not yet provide the needed <tt>CurrentWaveSpeed()</tt> code. These materials, which will update in the future as needed, are:

			* [[Isotropic, Hyperelastic-Plastic Material\|HEIsotropic]]
	* [[Isotropic, Elastic-Plastic Material\|IsoPlasticity]]		* [[Isotropic, Elastic-Plastic Material\|IsoPlasticity]]
	* [[Anisotropic, Elastic-Plastic Material\|HillPlastic]]		* [[Anisotropic, Elastic-Plastic Material\|HillPlastic]]
	* [[Mooney Material\|Mooney]]
	* [[Isotropic, Hyperelastic-Plastic Material\|HEIsotropic]]
	* [[Anisotropic, Hyperelastic Material\|HEAnisotropic]]		* [[Anisotropic, Hyperelastic Material\|HEAnisotropic]]

	All other materials have wave speed that is independent of particle state and therefore will only have dynamic adjustment of the time step on conditions where particles are approaching the initial wave speed of the material.		All other materials have wave speed that is independent of particle state and therefore will only have dynamic adjustment of the time step on conditions where particles are approaching the initial wave speed of the material.