Study and Study Step Types
To add a study or study step, see these topics:
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Creating a New Model
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The Add Study Window
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The Model Wizard
The main study step types — most of them available as a study in the Add Study window — are listed in Table 20-2. Some studies require add-on modules, and these are listed in Table 20-3 (in that list, the submenu under Study Steps in the Study branches appears in parentheses for the study types that are available as individual study steps).
Also see Study Extension Steps and Advanced Study Extension Steps for additional information about some study steps that do not generate equations and which can only be used in combination with other study steps. In Table 20-2, these are listed as supplemental studies and study steps.
Table 20-2: Standard Study types, Study Steps, and Study Extension Steps
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Study or Study Step
Brief Description
Empty Study
An Empty Study creates a Study node with no study steps.
General Studies
Studies that are generally available, such as Stationary and Time Dependent.
Preset Studies/Preset Studies for Selected Physics Interfaces
If you have added a single physics interface, you find suggested studies under this node.
If you have added multiple physics interfaces, you find studies applicable to all physics interfaces that you have added.
More Studies
This branch contains study types for which the selected physics interfaces are not automatically adapted. Instead, these physics interfaces have to be adapted manually using the Model Builder.
Preset Studies for Some Physics Interfaces
Under this node, studies applicable to all physics interfaces that you have chosen to solve for appear.
Preset Studies for Selected Multiphysics
Under this node, studies applicable to the multiphysics couplings that you have chosen to solve for appear.
Suggested by Some Physics Interfaces
Under this node (under Preset Studies for Selected Physics Interfaces), study types common to more than one physics interface appear if you have added more than two physics interfaces.
Name of physics interface
Under a node with the name of a physics interface under Preset Studies for Selected Physics Interfaces, study types specific to that physics interface appears.
Stationary Study Steps Submenu
Stationary
For a stationary or steady-state situation where you can use a stationary solver. This study type is also used for optimization problems that are constrained with a stationary PDE. Adds a Stationary study step. You can also choose to create a parametric continuation solver.
Time Dependent Study Steps Submenu
Time Dependent
For a time-dependent or transient simulation using a Time-Dependent Solver for computing the solution over time. This study type is also used for optimization problems that are constrained with a time-dependent PDE. Adds a Time Dependent study step.
Time Discrete
Only available as a Time Dependent study step. Use it to perform time-dependent analysis using the projection method.
Frequency to Time FFT
This study step performs an FFT (or nonuniform Fourier transform) from the frequency domain (the input) to the time domain for a time-dependent study.
Eigenfrequency Study Steps Submenu
Eigenfrequency
This study is similar to an Eigenvalue study but computes the eigenfrequencies instead of the eigenvalues. Adds an Eigenfrequency study step.
Eigenvalue
This study uses a formulation to compute eigenvalues and eigenmodes using an eigenvalue solver. Adds an Eigenvalue study step.
Frequency Domain Study Steps Submenu
Frequency Domain
For a study in the frequency domain such as wave equations or frequency response analysis. Adds a Frequency Domain study step.
Frequency Domain Perturbation
Use this study step for studies of small oscillations about a bias solution. This study step follows a study step that computes the stationary (or bias) solution and computes a perturbed solution of the linearized problem around the linearization point (or bias point) computed in the first step.
Time to Frequency FFT
This study step performs an FFT from the time domain (the input) to the frequency domain (output) for a frequency-domain study.
Study Extensions Steps
Batch
Use this step to start a COMSOL Multiphysics batch process that solves the current study on your computer.
Batch Sweep
Use this step to find the solution to a sequence of stationary or time-dependent simulations that arise when you vary some parameters of interest.
Cluster Computing
Use this step when you want to submit COMSOL Multiphysics batch jobs to a job scheduler that in turn runs the batch job on a second computer or cluster.
Cluster Sweep
Use this step to find the solution to a sequence of stationary or time-dependent simulations that arise when you vary some parameters of interest.
Combine Solutions
Use this step to combine two solutions; for example, two time-dependent simulations over two different time spans that you want to postprocess as a single time-dependent solution.
Function Sweep
This is a special case of Parametric Sweep study step, where the solver sweeps over functions defined under a Switch node defined under Global Definitions>Functions.
Material Sweep
This is a special case of Parametric Sweep, where the solver sweeps over materials defined under a Switch node defined under Materials.
Model Reduction
Use this step to create a reduced-order model from a time-dependent or frequency-domain simulation.
Multigrid Level
This can be added as a subnode to other study step nodes to describe a geometric multigrid level used by the study.
Parametric Sweep
Use this step to find the solution to a sequence of stationary or time-dependent problems that arise when you vary some parameters of interest. Add to a study to perform a parametric variation on other studies.
Sensitivity
Use this step to add a sensitivity analysis to the study. Using a Sensitivity study node you can add sensitivity functions at the study level and use model parameters as global control variables.
Study Reference
Use this step to refer to another study in the model.
 
Table 20-3: Studies and Study Steps Available with Add-on Modules
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Study or Study Step
Description
Required Module
Chemical Applications
AC Impedance, Initial Values
The AC Impedance Initial Values study is used for electrochemical impedance spectroscopy (EIS) computations in electrochemical cells.
The study consists of a single Frequency Domain Perturbation study step, which solves for a harmonic linear perturbation.
Batteries & Fuel Cells Module, Corrosion Module, Electrochemistry Module, or Electrodeposition Module.
AC Impedance, Stationary
Two study steps solve for a stationary problem and a harmonic perturbation in the frequency domain of the stationary solution.
Batteries & Fuel Cells Module, Corrosion Module, Electrochemistry Module, or Electrodeposition Module.
AC Impedance, Time Dependent
Two study steps solve for a time-dependent problem and a harmonic perturbation in the frequency domain of the solution at the last time step.
Batteries & Fuel Cells Module, Corrosion Module, Electrochemistry Module, or Electrodeposition Module.
Cyclic Voltammetry (under Time Dependent)
This study uses the Electroanalysis interface to perform transient simulations of voltammetry experiments.
Batteries & Fuel Cells Module, Corrosion Module, Electrochemistry Module, or Electrodeposition Module.
Stationary Plug Flow (under Stationary)
This study is used for plug flow reactor models created with the Reaction Engineering interface. It is used to solve for the molar flow rate as a function of reactor volume.
Chemical Reaction Engineering Module
Time-Dependent with Initialization
Use this study to perform transient simulations of electrochemical cells. It solves for the electrode and electrolyte potentials as well as all global ODE dependent variables. It also performs a transient simulation for all dependent variables in the model, using the result of the first study step as initial values.
Corrosion Module or Electrodeposition Module
Time-Dependent, Fixed Geometry
Use this study to exclude geometry deformation effects from a model. The study is similar to the Time-Dependent with Initialization study.
Corrosion Module or Electrodeposition Module
Electrical and Optical Applications
Bidirectionally Coupled Particle Tracing
This study is used to model the interactions of particle or ray trajectories with stationary fields. The study creates a Time Dependent solver that solves for all degrees of freedom related to the particles or rays. All other degrees of freedom are computed using a Stationary solver. The two solvers are repeated using a For-End For loop so that a self-consistent solution is obtained, taking the bidirectional coupling between the moving particles or rays and stationary fields into account.
Particle Tracing Module
Bidirectionally Coupled Ray Tracing
This study is used to compute ray trajectories that are affected by external fields. This study solves for all degrees of freedom related to rays using a Time-Dependent solver. All other degrees of freedom are computed using a Stationary solver. The two solvers are repeated using a For-End For loop so that a self-consistent solution is obtained, taking the bidirectional coupling between the propagating rays and stationary fields into account.
Ray Optics Module
Boundary Mode Analysis
Combines a mode analysis on a port (boundary) with a frequency domain study for the full geometry. Adds a Boundary Mode Analysis study step followed by a Frequency Domain study step.
RF Module or Wave Optics Module
Coil Geometry Analysis
Use this study to solve an eigenvalue problem for the current flow in a Multi-Turn Coil Domain node that gives the current density likely produced by a bundle of conductive wires.
AC/DC Module
Frequency-Stationary
This is a special case of a Stationary study and is available with the Induction Heating, Microwave Heating, and Laser Heating interfaces.
AC/DC Module, RF Module, or Wave Optics Module
Frequency-Transient
Compute electromagnetic fields in the frequency domain and the temperature (or electron temperature) in the time domain. Available with the Induction Heating, Microwave Heating, Inductively Coupled Plasma, and Microwave Plasma interfaces.
AC/DC Module, Plasma Module, RF Module, or Wave Optics Module
Mean Energies (under Frequency Domain)
Use this study to enter an array of values for the mean electron energy. Available with the Boltzmann Equation, Two-Term Approximation interface.
Plasma Module
Ray Tracing
Computes the trajectories of rays. This is a special case of the Time Dependent study step. The time list can either be specified directly or by entering a list of lengths and a characteristic group velocity. Built-in stop conditions can be used to stop the solver when no active rays remain, or when the intensity of active rays is negligibly small.
Ray Optics Module or Acoustics Module
Reduced Electric Fields (under Frequency Domain)
Use this study to sweep through a range of reduced electric fields. Available with the Boltzmann Equation, Two-Term Approximation interface.
Plasma Module
Schrödinger-Poisson
Use this study for the self consistent solution to the Schrödinger-Poisson system.
Semiconductor Module
Semiconductor Equilibrium
Use it to solve Poisson’s equation for the case where the charge carriers are in thermal equilibrium.
Semiconductor Module
Semiconductor Initialization
Use it to adaptively refine the mesh based upon the gradient of the impurity doping concentration.
Semiconductor Module
Sequential Frequency-Stationary
First solve a frequency-domain equation for electromagnetics and then use the electromagnetic heat source as a source term when solving a subsequent stationary heat transfer equation. Available with the Induction Heating, Microwave Heating, or Laser Heating interfaces.
AC/DC Module, RF Module, or Wave Optics Module
Sequential Frequency-Transient
Sequentially compute electromagnetic fields in the frequency domain and then the temperature (or electron temperature) in the time domain. Available with the Induction Heating, Microwave Heating, and Laser Heating interfaces.
AC/DC Module, RF Module, or Wave Optics Module
Stationary Source Sweep
A stationary source sweep to extract lumped matrices such as a capacity matrix in Electrostatics.
AC/DC Module
Time Dependent, Modal
This study is for analyzing time-dependent wave problems using a modal solver. The Time Dependent, Modal study adds an Eigenfrequency study step followed by a Time Dependent, Modal study step.
RF Module, Acoustics Module, MEMS Module, Structural Mechanics Module, or Wave Optics Module.
EEDF Initialization
The EEDF Initialization study is used to compute the electron energy distribution function (EEDF) without solving for the other plasma degrees of freedom. It can also be used to compute the initial EEDF for a time and space dependent plasma model.
Plasma Module
Time Periodic
This study solves for the periodic steady-state solution in model using the Plasma, Time Periodic interface.
Plasma Module
Time Periodic to Time Dependent
This study converts a time-periodic solution to a time-dependent solution in a model using the Plasma, Time Periodic interface.
Plasma Module
Wavelength Domain
Use this study to compute the response of a linear or linearized model subjected to electromagnetic harmonic excitation for one or several wavelengths.
Wave Optics Module
Fluid Applications
Frozen Rotor
This is a special case of a Stationary study. The frozen rotor approach assumes that the flow in the rotating domain, expressed in the rotating coordinate system, is fully developed. Available with the Rotating Machinery, Laminar Flow, and Turbulent Flow interfaces.
CFD Module or Mixer Module
Frozen Rotor with Initialization
For flow in rotating machinery where the topology of the geometry does not change with rotation. You can also use it to compute the initial conditions for time-dependent simulations of flow in rotating machinery.
CFD Module or Mixer Module
Stationary Free Surface
A study step added to a Frozen Rotor or Frozen Rotor with Initialization study to solve for the free surface deformation.
CFD Module
Stationary with Initialization
For stationary turbulent flow models that require an initialization.
CFD Module or Heat Transfer Module
Time Dependent with Initialization
For time-dependent turbulent flow models that require an initialization.
CFD Module or Heat Transfer Module
Thermal Perturbation, Eigenfrequency
For computing the oscillations around an equilibrium steady-state temperature field using: a Stationary study step followed by an Eigenfrequency study step.
Heat Transfer Module
Thermal Perturbation, Frequency Domain
For computing the oscillations around an equilibrium steady-state temperature field using: a Stationary study step followed by a Frequency-Domain, Perturbation study step.
Heat Transfer Module
Time Dependent with Phase Initialization
For time-dependent two-phase flow models that require an initialization of a level set function or phase field function.
CFD Module or Microfluidics Module
Stationary, One-Way Coupled, NITF
Two stationary study steps, one solving for the fluid flow variables and one solving for the heat transfer variables. Available with the Nonisothermal Flow and the Conjugate Heat Transfer interfaces.
CFD Module or Heat Transfer Module
Time Dependent, One-Way Coupled, NITF
Two time dependent study steps, one solving for the fluid flow variables and one solving for the heat transfer variables in the time domain. Available with the Nonisothermal Flow and the Conjugate Heat Transfer interfaces.
CFD Module or Heat Transfer Module
Frozen Rotor, One-Way Coupled, NITF
Two frozen rotor study steps, one solving for the fluid flow variables and one solving for the heat transfer variables. Available with the Rotating Machinery, Nonisothermal Flow interfaces.
Mixer Module plus CFD Module
Stationary, One-Way Coupled with Initialization, NITF
A wall distance initialization followed by two stationary study steps, one solving for the fluid flow variables and one solving for the heat transfer variables. Available with the Nonisothermal Flow and the Conjugate Heat Transfer interfaces.
CFD Module or Heat Transfer Module
Time Dependent, One-Way Coupled with Initialization, NITF
A wall distance initialization followed by two time dependent study steps, one solving for the fluid flow variables and one solving for the heat transfer variables in the time domain. Available with the Nonisothermal Flow and the Conjugate Heat Transfer interfaces.
CFD Module or Heat Transfer Module
Frozen Rotor, One-Way Coupled with Initialization, NITF
Two frozen rotor study steps, one solving for the fluid flow variables and one solving for the heat transfer variables. Available with the Rotating Machinery, Nonisothermal Flow interfaces.
Mixer Module plus CFD Module
Stationary, One-Way Coupled, MF
Two study steps, one solving for the fluid flow variables and one solving for the moisture transport variables. Available with the Moisture Flow interface.
Heat Transfer Module
Time Dependent, One-Way Coupled, MF
Two study steps, one solving for the fluid flow variables and one solving for the moisture transport variables in the time domain. Available with the Moisture Flow interface.
Heat Transfer Module
Mechanical Applications
Bolt Pretension
This study step is a special case of a Stationary study step, where the special degrees of freedoms used for modeling prestressed bolts are solved for.
Structural Mechanics Module
Fatigue
Use this study for fatigue evaluation. It processes a load cycle and evaluates a fatigue criterion specified in the Fatigue interface.
Structural Mechanics Module plus Fatigue Module
Linear Buckling
Use this study for a structural model to solve for the critical load factor using an eigenvalue solver.
Structural Mechanics Module or MEMS Module
Eigenfrequency, Prestressed
For computing eigenfrequencies that are influenced by a prior static load.
Structural Mechanics Module, Geomechanics Module, MEMS Module, or Acoustics Module
Frequency Domain, Prestressed
For computing the response to harmonic loads fluctuating around a static preload.
Frequency Domain, Prestressed, Modal
Three study steps are used to compute the response to harmonic loads fluctuating around a prior static load. The solution is performed using modal superposition.
Structural Mechanics Module, Acoustics Module, or MEMS Module
Response Spectrum
Adds a Response Spectrum node under Definitions and an Eigenfrequency study step for a response-spectrum analysis.
Structural Mechanics Module
Time Dependent, Prestressed, Modal
Three study steps are used to compute the response to time-dependent loads fluctuating around a prior static load. The solution is performed using modal superposition.
Structural Mechanics Module, Acoustics Module, or MEMS Module
Stationary, One-Way Coupled
Two study steps solve for the fluid flow variables and for the solid deformation. Available with the Fluid-Structure Interaction interface.
MEMS Module or Structural Mechanics Module
Time Dependent, One-Way Coupled
Two study steps solve for the fluid flow variables and for the solid deformation in the time domain. Available with the Fluid-Structure Interaction interface.
Stationary, One-Way Coupled with Initialization
Three study steps solve for the distance to the closest wall, for the fluid flow variables, and for the solid deformation. Available with the Fluid-Structure Interaction interface.
MEMS Module or Structural Mechanics Module, plus the CFD Module
Time Dependent, One-Way Coupled with Initialization
Three study steps solve for the distance to the closest wall, for the fluid flow variables, and for the solid deformation in the time domain. Available with the Fluid-Structure Interaction interface.
Time Dependent with FFT
Two study steps for computing a time-dependent solution using a Time Dependent study step and then applying a Time to Frequency FFT study step. Available with the Solid Rotor and Beam Rotor interfaces.
Rotordynamics Module
Multipurpose Applications
Adaptive Frequency Sweep
The Adaptive Frequency Sweep study is for analyzing the frequency response of a linear or linearized model subjected to harmonic excitation in the frequency domain using an AWE solver.
MEMS Module, RF Module, or Wave Optics Module
Frequency Domain, Modal
The Frequency Domain, Modal study is for analyzing wave problems in the frequency domain using a modal solver. It adds an Eigenfrequency study step followed by a Frequency Domain, Modal study step.
Structural Mechanics Module, MEMS Module, Acoustics Module, RF Module, or Wave Optics Module
Mode Analysis
Computes the modes for an acoustic or electromagnetic wave using an eigenvalue solver.
Acoustics Module, RF Module, or Wave Optics Module
Modal Reduced-Order Model
As a study, it combines an Eigenfrequency study step with a Modal Reduced-Order Model study step. You can also add a Modal Reduced-Order Model study step to export the reduced-order model matrices for time-dependent wave problems using a modal solver. Available from the Study node under Study Steps>Time dependent.
Structural Mechanics Module, MEMS Module, Acoustics Module, RF Module, or Wave Optics Module
Optimization
Use this study to solve PDE-constrained optimization problems. This study step allows direct definition of objective functions and selection of model parameters, including parameters that control the geometry, for optimization. It also provides detailed control over solvers and contributions to an optimization problem defined by an Optimization interface.
Optimization Module
Parameter Estimation
This study provides parameter estimation for time-dependent models.
Optimization Module
Particle Trajectories (under Time Dependent)
This study has the same settings as the Time Dependent study step except that by default, only the Particle Tracing Module’s physics interfaces for particle tracing are active in the selection.
Particle Tracing Module
Small-Signal Analysis, Frequency Domain
For perturbed frequency domain studies of small oscillation about a bias solution. The study creates two study steps that solve for a stationary problem and for a harmonic perturbation in the frequency domain of the stationary solution.
AC/DC Module, MEMS Module, or Semiconductor Module