simulation

Simulation classes and helpers for evaluating kinetic models against data.

members:

class pyteck.simulation.BaseSimulation(kind, apparatus, meta, properties)

Abstract base class for a single simulation case of a kinetic model.

Subclasses implement a specific simulation type, e.g. a homogeneous reactor for autoignition delay or a one-dimensional flame for laminar burning velocity.

Parameters:

• kind (str) – Kind of experiment (e.g., ‘ignition delay’)

• apparatus (str) – Type of apparatus (e.g., ‘shock tube’)

• meta (dict) – Metadata for this case

• properties (pyked.chemked.DataPoint) – Set of properties for this case

clean()

Remove the intermediate results data file, if it exists.

abstractmethod process_results()

Process results to obtain the simulated metric.

abstractmethod run_case(restart=False)

Run the simulation case set up by setup_case.

Parameters:

restart (bool, optional) – If True, skip the case when its results file already exists (default: False).

abstractmethod setup_case(model_file, species_key, path='')

Set up the simulation case to be run.

Parameters:

• model_file (str or pathlib.Path) – Filename for Cantera-format model

• species_key (dict) – Dictionary with species names for model_file

• path (str or pathlib.Path, optional) – Directory in which to save any results data file. The default ("") uses the current working directory.

class pyteck.simulation.FlameSimulation(kind, apparatus, meta, properties)

One-dimensional freely propagating laminar flame simulation.

Placeholder for laminar burning velocity measurements. The corresponding PyKED schema is still in development (see PyKED PR #141), so this simulation type is not yet implemented.

process_results()

Process results to obtain the simulated metric.

run_case(restart=False)

Run the simulation case set up by setup_case.

Parameters:

restart (bool, optional) – If True, skip the case when its results file already exists (default: False).

setup_case(model_file, species_key, path='')

Set up the simulation case to be run.

Parameters:

• model_file (str or pathlib.Path) – Filename for Cantera-format model

• species_key (dict) – Dictionary with species names for model_file

• path (str or pathlib.Path, optional) – Directory in which to save any results data file. The default ("") uses the current working directory.

class pyteck.simulation.HomogeneousReactorSimulation(kind, apparatus, meta, properties)

Homogeneous (0-D) reactor simulation for autoignition delay.

Models shock tube and rapid compression machine ignition-delay experiments using a Cantera IdealGasReactor.

static create_volume_history(mech, temp, pres, reactants, pres_rise, time_end)

Construct a volume profile based on initial conditions and pressure rise.

Parameters:

• mech (str or pathlib.Path) – Cantera-format mechanism file (*.yaml)

• temp (float) – Initial temperature, in K

• pres (float) – Initial pressure, in Pa

• reactants (str) – Reactants composition in mole fraction

• pres_rise (float) – Pressure rise rate, in s^-1

• time_end (float) – End time of simulation, in s

Returns:

Times and computed volumes

Return type:

tuple of numpy.ndarray

static get_ignition_delay(time, target, target_name, ignition_type)

Identify ignition delay based on time, target, and type of detection.

Parameters:

• time (numpy.ndarray) – Times in s

• target (numpy.ndarray) – Values of target quantity of interest (e.g., temperature, pressure, species amount)

• target_name (str) – Name of target quantity of interest (e.g., ‘temperature’, ‘OH’)

• ignition_type (str) – ‘max’, ‘d/dt max’, ‘1/2 max’, or ‘d/dt max extrapolated’

Returns:

One or more calculated ignition delay times, in s

Return type:

numpy.ndarray

process_results()

Process integration results to obtain ignition delay.

run_case(restart=False)

Run simulation case set up by setup_case.

Parameters:

restart (bool, optional) – If True, skip the case when its results file already exists (default: False).

static sample_rising_pressure(time_end, init_pres, freq, pressure_rise_rate)

Samples pressure for particular frequency assuming linear rise.

Parameters:

• time_end (float) – End time of simulation, in seconds

• init_pres (float) – Initial pressure, in Pa

• freq (float) – Frequency of sampling, in Hz

• pressure_rise_rate (float) – Pressure rise rate, in s^-1

Returns:

Tuple of times and sampled pressures

Return type:

tuple of numpy.ndarray

setup_case(model_file, species_key, path='')

Sets up the simulation case to be run.

Parameters:

• model_file (str or pathlib.Path) – Filename for Cantera-format model

• species_key (dict) – Dictionary with species names for model_file

• path (str or pathlib.Path, optional) – Directory in which to save the results data file. The default ("") writes to the current working directory.

class pyteck.simulation.PressureRiseProfile(mech_filename, initial_temp, initial_pres, reactants, pressure_rise, time_end)

Set the velocity of reactor moving wall via specified pressure rise.

The initialization and calling of this class are handled by the Func1 interface of Cantera.

The approach used here is based on that discussed by Chaos and Dryer, “Chemical-kinetic modeling of ignition delay: Considerations in interpreting shock tube data”, Int J Chem Kinet 2010 42:143-150, doi:10.1002/kin.20471 <http://dx.doi.org/10.1002/kin.20471. A time-dependent polytropic state change is emulated by determining volume as a function of time, via a constant linear pressure rise \(A\) (given as a percentage of the initial pressure):

\[ \begin{align}\begin{aligned}\begin{split}\frac{dv}{dt} &= -\frac{1}{\gamma} \frac{v(t)}{P(t)} \frac{dP}{dt} \\ v(t) &= \frac{1}{\rho} \left[ \frac{P(t)}{P_0} \right]^{-1 / \gamma}\end{split}\\\begin{split}\frac{dP}{dt} &= A P_0 \\ \therefore P(t) &= P_0 (A t + 1)\end{split}\\\frac{dv}{dt} = -A \frac{1}{\rho \gamma} (A t + 1)^{-1 / \gamma}\end{aligned}\end{align} \]

The expression for \(\frac{dv}{dt}\) can then be used directly for the Wall velocity.

class pyteck.simulation.VolumeProfile(volume_history)

Set the velocity of reactor moving wall via specified volume profile.

The initialization and calling of this class are handled by the Func1 interface of Cantera.

Based on VolumeProfile implemented in Bryan W. Weber’s CanSen <http://bryanwweber.github.io/CanSen/>

pyteck.simulation.create_simulation(kind, apparatus, meta, properties)

Construct the appropriate BaseSimulation subclass for a case.

Parameters:

• kind (str) – Experiment/measurement type (e.g., ‘ignition delay’)

• apparatus (str) – Apparatus kind (e.g., ‘shock tube’)

• meta (dict) – Metadata for this case

• properties (pyked.chemked.DataPoint) – Object with full set of experimental properties for this case

Returns:

Simulation case of the appropriate subclass

Return type:

BaseSimulation