Boundary and Initial Conditions
Boundary conditions close the finite-volume equations at external faces. Initial conditions provide the starting state from which steady iteration or transient time integration begins. Boundary settings can directly change the physical problem; initialization settings should not change a unique converged steady solution, but they can strongly affect robustness and convergence time.
Theory reference. Each option entry includes a link to the corresponding equation, physical model, closure, or numerical method in the Theory Manual. Defaults, availability, simulation effects, and practical guidance are documented directly with the GUI option.
Use physically consistent variable sets. Compressible inlets distinguish total and static quantities; pressure outlets can use backflow values when the local flow reverses. Turbulence, species, particles and VOF composition are only requested when those models are active.
Boundary-condition type
The boundary type determines which characteristic/physical closure CMPS applies at each face zone.
| GUI option | Meaning / formulation | Effect on the simulation | Practical guidance | Theory reference |
|---|---|---|---|---|
| Wall | Closes the fluid domain at a solid boundary. For a stationary viscous wall, no-slip gives \(\mathbf u_w=0\); moving-wall velocity can be prescribed. Thermal behavior is selected separately. | PhysicsAccuracy Controls wall shear, boundary-layer development, heat transfer and forces. | Use a wall only on physical solid boundaries. Check wall motion and thermal mode carefully. | Wall boundary closure |
| Mass Flow Inlet | Prescribes the integrated mass rate, \(\dot m=\int_A\rho\,\mathbf u\cdot\mathbf n\,dA\), together with the thermodynamic quantities needed to determine the inlet state. | Physics Fixes the total mass supplied through the zone; local velocity/density adjust consistently with the inlet model. | Use when mass flow is known more reliably than velocity or upstream pressure. Ensure the sign/direction is correct. | Inlet boundary closure |
| Velocity Inlet | Prescribes velocity magnitude and direction, conceptually \(\mathbf u_b=U_b\hat{\mathbf d}\), plus temperature/composition as required. A zero direction vector can use the inward-normal convention. | Physics Directly controls inlet momentum and flow direction; mass flow follows density and area. | Use when the velocity field is known. Check direction on curved/inclined zones. | Inlet boundary closure |
| Pressure Outlet | Prescribes outlet static pressure and uses interior extrapolation for outgoing characteristics; when flow reverses, configured backflow properties are used. | PhysicsStability / convergence Sets downstream pressure level and can influence the entire compressible/pressure-driven solution. | Place sufficiently downstream of strong recirculation when possible. Define realistic backflow temperature/composition for possible reverse flow. | Pressure-outlet closure |
| Pressure Inlet | Prescribes upstream pressure information (total/static form depends on regime) and associated temperature/composition. | Physics Controls inflow through pressure difference and characteristic response rather than fixed mass rate. | Use for plenum/reservoir-driven inflow and compressible inlet problems. | Inlet boundary closure |
| Farfield | Prescribes an external freestream state using Mach number, static pressure, static temperature and direction. | PhysicsAccuracy Allows subsonic/supersonic characteristic response appropriate to an external boundary. | Use sufficiently far from the body/strong disturbances. | Far-field closure |
| Solid Propellant | Models a gas-generating solid surface with pressure/time-dependent surface mass addition and flame thermodynamic state. | PhysicsStability / convergence Adds mass, momentum/energy/species boundary fluxes and couples burning to chamber pressure when pressure-dependent law is used. | Use only with calibrated propellant data and consistent gas composition/temperature. | Solid-propellant surface |
| Axis | Applies the axis condition for an axisymmetric mesh. | Physics Enforces regularity/no flux through the symmetry axis and is required for the cylindrical formulation. | Assign only to the geometric axis. | Symmetry/axis closure |
| Symmetry | Enforces zero normal velocity/normal scalar flux while allowing tangential flow. Conceptually \(\mathbf u\cdot\mathbf n=0\). | PhysicsAccuracy Removes cross-plane transport and represents a mirror plane. | Use only when geometry and physics are symmetric; otherwise it artificially constrains the solution. | Symmetry/axis closure |
| Coupled Wall (FSI) | Creates the coupled wall interface used for fluid-solid thermal/interaction exchange where available. | PhysicsStability / convergence Transfers interface quantities rather than imposing a one-sided external wall state. | Use on matching interface zones intended to exchange heat/loads with the adjoining domain. | Wall boundary closure |
| Fluid Interior | Marks an internal transmissive fluid interface. | Physics Allows conservative flux between neighboring fluid cells instead of applying an external boundary law. | Use on genuine internal faces, not an external opening. | Interior/interface closure |
| Solid Interior | Marks an internal transmissive solid interface. | Physics Allows conductive energy transfer through the solid mesh without an external wall condition. | Use between connected solid regions as appropriate. | Interior/interface closure |
| Apply / Cancel | Apply commits edits to the selected zone; Cancel discards current uncommitted edits. | Initialization Apply changes the case definition; Cancel does not. | After applying, review the zone list and use copy tools only for genuinely identical boundaries. | Boundary-condition families |
| Boundary Copy Tool | Copies a configured boundary condition from one zone to selected compatible zones. | Initialization Can rapidly change multiple physical boundaries. | Use carefully: copied area, direction and local geometry can make identical scalar values physically different. | Boundary-condition families |
Inlet, outlet and farfield values
Open boundaries determine the external thermodynamic and momentum state that communicates with the domain.
| GUI option | Meaning / formulation | Effect on the simulation | Practical guidance | Theory reference |
|---|---|---|---|---|
| Mass Flow Rate [kg/s] | Target integrated mass flow for a mass-flow inlet. | Physics Directly sets inlet mass supply. Higher rate increases momentum/throughput and can change pressure field strongly. | Use the total for the selected zone, not a per-area value unless the GUI field explicitly requests one. | Inlet boundary relations |
| Inlet Temperature | For compressible mass-flow/pressure inlets the GUI uses the required total/static temperature form; for constant-density inlet the static temperature is used. | Physics Controls inlet enthalpy and therefore density, sound speed, energy and reaction/heat-transfer state. | Confirm whether total or static temperature is requested for the selected boundary/regime. | Inlet boundary relations |
| Reference Total Pressure | Reference/upstream total-pressure information used by applicable inlet formulation. | PhysicsStability / convergence Influences compressible inlet state and can also be used by pressure-ratio/preconditioning acceleration logic. | Use a physically consistent stagnation pressure. | Inlet boundary relations |
| Supersonic Gauge Pressure | Additional pressure specification used when all characteristics enter through a supersonic inlet. | Physics Directly fixes pressure in a fully inflowing supersonic state. | Use only when the boundary is expected to be supersonic and all incoming variables are known. | Inlet boundary relations |
| Velocity Magnitude | Sets \(U_b\) for a velocity inlet. | Physics Directly controls inlet momentum and mass flow. | Check resulting mass flow and Mach number after initialization. | Inlet boundary relations |
| Velocity Direction X/Y/Z | Defines the inlet unit direction after normalization. | PhysicsAccuracy Controls flow angle and therefore momentum components, incidence and swirl/crossflow. | Use the inward direction relative to the boundary; verify with velocity vectors. | Inlet boundary relations |
| Pressure Outlet Static Pressure | Prescribed outlet pressure \(p_b\). | Physics Sets the downstream pressure reference and pressure ratio. | Use static, not total, pressure. Avoid placing the outlet inside strong shock/recirculation regions if possible. | Pressure-outlet closure |
| Pressure Specification: Forced | Uses the configured outlet pressure as a direct target at the boundary. | PhysicsStability / convergence Stronger pressure enforcement can stabilize a known outlet pressure but may reflect disturbances more strongly if the boundary is poorly placed. | Use when the outlet pressure must be imposed explicitly. | Inlet boundary relations |
| Pressure Specification: Interpolated | Uses the outlet pressure through the interpolation/characteristic boundary treatment rather than a direct face target. | PhysicsStability / convergence Can provide a smoother extrapolative outlet response depending on local flow state. | Use when a less forcibly imposed outlet state is appropriate and validate mass/pressure behavior. | Inlet boundary relations |
| Backflow Temperature | Temperature used if a pressure outlet locally reverses and becomes inflowing; the compressible formulation uses the required backflow thermodynamic form. | PhysicsStability / convergence Only affects reversed portions of the outlet, but unrealistic values can destabilize recirculating outlets. | Set to a realistic external/plenum value even if backflow is not expected. | Pressure-outlet closure |
| Pressure Inlet Pressure | Sets the pressure information for pressure-driven inflow. | Physics Mass flow becomes an outcome of upstream/downstream pressure and flow resistance. | Use when pressure is the physically controlled inlet quantity. | Inlet boundary relations |
| Farfield Mach Number | Sets freestream speed through \(M_\infty=|\mathbf u_\infty|/a_\infty\). | Physics Controls compressibility, dynamic pressure and characteristic direction at farfield faces. | Use together with static pressure/temperature and direction. | Far-field closure |
| Farfield Static Pressure / Temperature | Defines freestream thermodynamic state. | Physics Controls density, sound speed, viscosity/properties and reference pressure level. | Use ambient/free-stream static conditions, not stagnation values. | Far-field closure |
| Farfield Direction X/Y/Z | Defines freestream flow direction. | PhysicsAccuracy Controls angle of attack/sideslip relative to the geometry. | Normalize/verify the vector and use consistent force-reference axes. | Far-field closure |
| Constant / profile boundary value | Where supported, a scalar can be constant or supplied by the GUI-configured spatial/time profile. | PhysicsInitialization A profile can make boundary data vary with position/time and therefore changes the physical forcing. | Use profiles for known nonuniform/transient boundary data; verify units and coordinates with a simple test case. | Boundary profiles |
Wall thermal conditions
The wall thermal mode controls heat flux or temperature closure at each wall.
| GUI option | Meaning / formulation | Effect on the simulation | Practical guidance | Theory reference |
|---|---|---|---|---|
| Wall Velocity X/Y/ZDefault: 0 for stationary wall | Prescribes moving-wall velocity. No-slip uses the wall velocity as the fluid tangential velocity at the wall. | Physics Generates shear/work from wall motion and can drive Couette/rotating-belt-type flow. | Set zero for a stationary wall. For rotating zones, distinguish MRF grid motion from an explicitly moving physical wall. | Wall thermal-condition families |
| Adiabatic WallDefault: Common default wall thermal condition | Imposes zero conductive heat flux, \(q_w=0\). | Physics Wall temperature becomes a solution outcome of fluid/solid state; no external heat crosses the boundary. | Use for insulated walls or when heat transfer through the surface is intentionally neglected. | Wall thermal-condition families |
| Constant Temperature Wall | Prescribes \(T_w\). | PhysicsAccuracy Directly controls wall thermal state and heat flux; can strongly influence density, viscosity, reactions and boundary layer. | Use when wall temperature is externally maintained/known. | Wall thermal-condition families |
| Convective Heat Transfer | Uses \(q=h(T_\infty-T_w)\) with convection coefficient \(h\) and ambient temperature \(T_\infty\). | PhysicsAccuracy Couples wall heat flux to wall temperature and external environment; larger \(h\) drives \(T_w\) more strongly toward ambient. | Use for an unresolved external convection environment. Provide physically based \(h\). | Wall thermal-condition families |
| Convection Coefficient h | Coefficient in \(q=h(T_\infty-T_w)\). | PhysicsAccuracy Higher \(h\) increases external convective heat transfer. | Use a coefficient appropriate to the unresolved side, geometry and flow regime. | Wall thermal-condition families |
| Convective Ambient Temperature | External fluid temperature \(T_\infty\) for the convection law. | Physics Sets the direction/magnitude of external convective heat flow relative to \(T_w\). | Use the effective ambient/bulk temperature for the correlation. | Wall thermal-condition families |
| Constant Heat Flux | Prescribes wall heat flux \(q\); GUI convention is positive inward and negative outward. | Physics Adds/removes thermal energy at a fixed rate per area independent of wall temperature. | Check the sign carefully. Use when heater/cooling flux is known. | Wall thermal-condition families |
| External Radiation | Uses net radiation approximately \(q_{rad}=\epsilon\sigma(T_{rad}^4-T_w^4)\). | PhysicsStability / convergence Strongly nonlinear with temperature; can dominate at high temperatures. | Use absolute Kelvin temperatures and realistic emissivity/environment temperature. | Wall thermal-condition families |
| Radiation Ambient Temperature | The radiative surroundings temperature \(T_{rad}\). | Physics Changes incident/emitted net radiative balance through the fourth power. | Use an effective radiative environment temperature, not necessarily local air temperature. | Wall thermal-condition families |
| Emissivity | Surface emissivity \(0\le\epsilon\le1\) in the radiation law. | PhysicsAccuracy Linearly scales net radiative exchange. | Use material/surface-condition data; polished and oxidized surfaces can differ strongly. | Wall thermal-condition families |
| External Mixed | Combines supported external convection and radiation contributions. | PhysicsAccuracyStability / convergence Wall thermal balance includes both mechanisms and can be strongly nonlinear. | Use when both unresolved external convection and radiation matter. | Wall thermal-condition families |
| One-Dimensional Charring | Activates the boundary-attached through-thickness charring/pyrolysis material response. | PhysicsCost Adds transient internal wall material conduction/reaction and couples surface thermal response to material degradation. | Use only for the intended ablative/charring material model with calibrated properties. | Wall thermal-condition families |
Turbulence, species, particle and VOF boundary data
Additional tabs appear when the corresponding physical model is active.
| GUI option | Meaning / formulation | Effect on the simulation | Practical guidance | Theory reference |
|---|---|---|---|---|
| Turbulence input: Kinetic Energy | Prescribes turbulent kinetic energy \(k\) directly at an inlet/backflow boundary. | Physics Directly sets turbulence energy level and influences eddy viscosity. | Use when \(k\) is known from data or a precursor simulation. | Turbulence inlet relations |
| Turbulence input: Turbulent Intensity | Computes inlet kinetic energy from intensity, \(k=\tfrac32(U_n I)^2\). | PhysicsAccuracy Higher intensity increases inlet turbulence level, mixing and often turbulent viscosity. | Use measured/estimated intensity appropriate to the inflow facility/environment. | Turbulence inlet relations |
| ω directly | Prescribes specific dissipation rate \(\omega\). | Physics Sets turbulence time/length scale together with \(k\). | Use when \(\omega\) is known. | Turbulence inlet relations |
| Length Scale | Computes \(\omega=\sqrt{k}/(C_\mu^{1/4}L_t)\). | PhysicsAccuracy Smaller \(L_t\) gives larger \(\omega\) and usually smaller turbulent length scale/eddy viscosity. | Estimate from inlet geometry or measured integral scale. | Turbulence inlet relations |
| Viscosity Ratio | Uses the specified \(\mu_t/\mu\) to infer \(\omega=\rho k/[\mu(\mu_t/\mu)]\). | PhysicsAccuracy Directly controls initial/inlet eddy-viscosity level. | Convenient when turbulence viscosity ratio is known more reliably than a length scale. | Turbulence inlet relations |
| Species Mass Fractions | Prescribes the independent species fractions; the last species closes the sum to one. | Physics Sets inlet/backflow mixture molecular weight, thermodynamics and reaction mixture. | Ensure nonnegative fractions and a physically consistent sum. | Species boundary state |
| Particle Mass Fraction / Temperature / Diameter | Prescribes dispersed-phase inflow/backflow state when the dispersed model is active. | Physics Controls particle loading, thermal coupling, drag/heat-transfer scales and IATE initial size. | Use consistent loading and material diameter data; avoid nonphysical values below solver floors. | Dispersed boundary state |
| VOF Composition | Prescribes physical phase fractions at inlet-like boundaries and for pressure-outlet backflow. | Physics Directly sets which phase enters the domain and therefore mixture EOS/properties. | Ensure the phase fractions form a valid simplex and match the intended reference phase. | VOF boundary composition |
Solid-propellant boundary controls
Propellant boundary options determine gas generation and thermal injection from a burning surface.
| GUI option | Meaning / formulation | Effect on the simulation | Practical guidance | Theory reference |
|---|---|---|---|---|
| Pressure-dependent propellant law | Uses a pressure power law of the form \(\dot m_g=a_b p_f^{n_b}\rho_p(1-f_c)\) for gas generation at the surface. | PhysicsStability / convergence Creates pressure-burning feedback: higher chamber pressure changes surface mass generation according to exponent \(n_b\). | Use calibrated \(a_b,n_b,\rho_p\) and the correct pressure units/range. | Solid-propellant boundary model |
| Propellant coefficient a | Pre-exponential/burning-rate coefficient in the pressure law. | PhysicsAccuracy Scales mass generation directly. | Use material test data. | Solid-propellant boundary model |
| Propellant exponent n | Pressure exponent in \(p^n\). | PhysicsStability / convergenceAccuracy Controls sensitivity of burning rate to pressure and therefore chamber feedback/stability. | Use calibrated data; small changes can materially alter coupled pressure. | Solid-propellant boundary model |
| Propellant density | Solid propellant density multiplying the regression/burning rate to obtain mass flux. | Physics Directly scales generated mass flux for a given burn rate. | Use bulk propellant density. | Solid-propellant boundary model |
| Flame Temperature | Thermal state assigned to generated gas. | PhysicsAccuracy Controls injected enthalpy/energy and can strongly affect chamber temperature and pressure. | Use the model-consistent flame/gas temperature. | Solid-propellant boundary model |
| Time Dependent Polynomial Mass Flow Rate | Prescribes the total boundary mass-flow history from the three GUI polynomial ranges. The returned function is converted to gas mass flux by dividing by boundary area and multiplying by the gas fraction. | PhysicsAccuracy Replaces pressure-coupled burning with a prescribed time history; pressure no longer determines the imposed mass-flow value. | Use only for a known imposed transient history and verify the resulting total mass flow in a surface report. | Solid-propellant boundary model |
| Time Dependent Polynomial Total Pressure | Prescribes the propellant-boundary total-pressure history from the same three-range time function. The boundary then behaves as a time-varying stagnation inlet. | PhysicsAccuracyStability / convergence Directly forces chamber inflow total pressure and can produce strong transients when the prescribed history changes rapidly. | Use smooth, physically supported pressure histories and resolve transitions with the physical time step. | Solid-propellant boundary model |
| Time Polynomials Range 1 / 2 / 3: t_limitDefault: Defaults stored as 0, 0.1 and 0.3 s for the three displayed fields | Three GUI range-limit fields are stored. In the active three-range selector, the Range-2 limit is the first switching time and the Range-3 limit is the second switching time; the Range-1 limit is stored but does not participate in the current branch selection. | PhysicsAccuracy Changing the second/third limits changes when the prescribed history switches coefficient sets. Changing the first displayed limit currently does not change the evaluated history. | Treat the Range-2 and Range-3 limits as the two active transition times. Do not rely on the Range-1 limit to truncate the first range. | Solid-propellant boundary model |
| Time Polynomials Range 1 / 2 / 3: t^0 ... t^4 coefficientsDefault: All coefficients initially zero | For the selected range the current CMPS evaluator uses \(g_r(t)=c_{r,0}t+\sum_{m=1}^{4}c_{r,m}t^m\). Therefore the GUI field labelled \(t^0\) currently multiplies time rather than acting as a constant offset; the \(t^1\) field also contributes a linear term. | PhysicsAccuracyStability / convergence The coefficient interpretation directly defines the imposed mass-flow or total-pressure history. Assuming the first field is a constant term would produce a different boundary forcing than intended. | Plot/check the prescribed history before production runs. Enter coefficients according to the formula shown here, not according to the field superscript alone. | Solid-propellant boundary model |
| Solid Propellant Particle FractionDefault: 0 | Sets the non-gas fraction of the propellant-generated mass stream. The gas contribution is multiplied by \(1-f_p\). | PhysicsAccuracy Increasing the fraction reduces the gaseous mass/enthalpy injected by the propellant surface and changes dispersed loading when the particle path is active. | Use the physical condensed-particle mass fraction and keep it in the admissible interval. | Solid-propellant boundary model |
| FSI Thermal BC: Adiabatic / Coupled Wall | For a coupled fluid-solid wall, selects either zero interfacial thermal exchange or conjugate thermal coupling to the neighboring solid. | PhysicsAccuracy Adiabatic blocks heat transfer. Coupled Wall transfers heat between fluid and solid and can materially change wall and fluid temperatures. | Use Coupled Wall only on a correctly paired fluid-solid interface with a valid solid material/initial temperature. | Solid-propellant boundary model |
| Particle Mass Flow Rate / Particle Mass Fraction | Depending on the boundary editor/context, the dispersed inlet loading is entered either as a total particle mass-flow rate or as a particle mass fraction/loading variable. | PhysicsAccuracy Sets the amount of dispersed material entering through the boundary and therefore drag, heat-transfer and mass coupling. | Confirm which field is shown for the selected boundary type and verify the resulting particle mass flow with a report. | Solid-propellant boundary model |
One-dimensional charring-material controls
These settings are shown when the wall thermal mode uses the charring response.
| GUI option | Meaning / formulation | Effect on the simulation | Practical guidance | Theory reference |
|---|---|---|---|---|
| Material thickness | Through-thickness depth of the one-dimensional material model. | PhysicsAccuracy Changes thermal diffusion time, available virgin/char material and back-face influence. | Use actual local material thickness represented by the boundary model. | One-dimensional charring response |
| Material nodesDefault: 3–501 allowed | Number of 1D nodes across the thickness. | AccuracyCost Higher count resolves thermal/reaction gradients better but increases per-wall computational work. | Refine until surface heat flux/temperature and recession-related response are insensitive. | One-dimensional charring response |
| Initial material temperature | Initial temperature profile baseline for the 1D material. | PhysicsInitialization Controls initial stored energy and early transient response. | Use actual pre-exposure material temperature. | One-dimensional charring response |
| Steady exposure time | Exposure/initialization duration used by the charring-material setup where applicable. | PhysicsInitialization Can precondition the material response toward an exposed state. | Use only when representing prior exposure. | One-dimensional charring response |
| Maximum material time step | Caps the internal 1D material integration time step. | AccuracyStability / convergenceCost Smaller values improve temporal resolution/robustness of stiff pyrolysis at higher cost. | Reduce if temperature/reaction response is unstable or under-resolved. | One-dimensional charring response |
| Back-face: Adiabatic | Uses zero heat flux at the back surface. | Physics Represents perfect back insulation and tends to retain heat in the material. | Use when backing losses are negligible. | One-dimensional charring response |
| Back-face: Fixed Temperature | Prescribes back-face temperature. | Physics Adds a strong thermal sink/source and can materially alter through-thickness temperature. | Use when the backing structure is maintained near a known temperature. | One-dimensional charring response |
| Virgin / Char Density | Densities for undecomposed and charred material states. | PhysicsAccuracy Affect volumetric heat capacity, mass loss and material response as reaction progresses. | Use measured material data. | One-dimensional charring response |
| Virgin / Char Conductivity | Thermal conductivities of virgin/char states. | PhysicsAccuracy Control heat penetration and surface/back-face temperature response. | Use temperature-dependent data where required by the material model. | One-dimensional charring response |
| Virgin / Char Specific Heat | Heat capacities of virgin/char states. | PhysicsAccuracy Control thermal inertia and temperature rise. | Use consistent thermophysical data. | One-dimensional charring response |
| Arrhenius A / Activation Energy E / Reaction Order n | Defines the pyrolysis progress rate \(\dot\alpha=A\exp[-E/(RT)](1-\alpha)^n\). | PhysicsStability / convergenceAccuracy Controls onset temperature, rate and sharpness of decomposition; can be very stiff. | Use calibrated decomposition kinetics, not generic values. | One-dimensional charring response |
| Pyrolysis Enthalpy | Appears in the material energy balance, conceptually \(\rho c_p\partial_tT=\partial_x(k\partial_xT)-\dot m_{pyro}\Delta h_{pyro}\). | PhysicsAccuracy Controls thermal energy absorbed/released by decomposition. | Use thermochemically consistent sign and magnitude. | One-dimensional charring response |
Initial conditions and initialization actions
Initial conditions primarily affect startup and transient history; they can also select a different physical transient if the problem is time-dependent.
| GUI option | Meaning / formulation | Effect on the simulation | Practical guidance | Theory reference |
|---|---|---|---|---|
| Initial Static Pressure | Initial cell pressure for fluid zones. | InitializationStability / convergence Sets starting density/pressure field and can strongly affect startup transients/nonlinear residual. | Use a field reasonably close to the expected operating pressure. | Initialization |
| Initial Temperature | Initial fluid/solid temperature. | InitializationStability / convergence Controls starting density/properties/energy and reacting rates. | Use physically realistic initial thermal state. | Initialization |
| Initial Velocity X/Y/Z | Initial velocity field. | InitializationStability / convergence A better velocity guess can reduce startup iterations; an inconsistent high velocity can trigger shocks/positivity limiting. | Use expected bulk direction/speed if known; zero is safe but may converge slower for high-speed cases. | Initialization |
| Initial Turbulence | Initial \(k\), intensity, \(\omega\), length scale or viscosity ratio as available. | InitializationPhysics Controls early turbulent viscosity/production and wall-model startup. | Use values consistent with inlet turbulence rather than numerical floors. | Initialization |
| Initial Species Composition | Initial mass fractions. | InitializationPhysics Sets initial mixture properties and reaction state. | Use a physically consistent mixture; for combustion, avoid an arbitrary reactive mixture unless intended. | Initialization |
| Initial Particle State | Initial particle loading, temperature and diameter for dispersed zones. | InitializationPhysics Sets initial drag/thermal/source coupling. | Use zero/near-zero only if the domain initially contains no dispersed phase. | Initialization |
| Initial VOF Composition | Initial phase fractions in VOF zones. | InitializationPhysicsAccuracy Defines initial interface location and mixture properties. | Use bounded fractions and a sharp/smoothed interface consistent with the intended initial condition. | Initialization |
| Hybrid Initialization | Builds an internally generated starting flow field from the configured case rather than relying solely on uniform manual values. | InitializationStability / convergence Can greatly improve initial pressure/velocity consistency and reduce startup difficulty. | Use as a general initializer, then inspect the field before solving. | Initialization |
| Initialize All Zones | Applies the configured initialization to every compatible zone. | Initialization Overwrites existing initial/loaded fields in those zones. | Do not use after loading a desired solution unless you intend to replace it. | Initialization |
| Initialize Selected Zones | Applies initialization only to selected zones. | Initialization Lets existing states be preserved elsewhere. | Useful for multi-zone/CHT cases and controlled restarts. | Initialization |
| Initial-Condition Copy Tool | Copies initial-condition settings between compatible zones. | Initialization Can quickly alter many zones. | Verify material/phase compatibility before copying. | Initialization |
Bulk edit and copy actions
These controls speed repetitive setup but can change many zones at once.
| GUI option | Meaning / formulation | Effect on the simulation | Practical guidance | Theory reference |
|---|---|---|---|---|
| Apply All Changes / Cancel All Changes | Commits all pending boundary/cell-condition edits in the corresponding option panel, or discards the pending edits. | InitializationPhysics Apply changes the case definition; Cancel leaves the previously committed case unchanged. | Use Apply All only after reviewing every selected zone. | Boundary conditions and face closures |
| Copy From | Selects the source zone used by the boundary-condition or initial-condition copy tool. | The source itself is not modified; its settings become the template for selected destination zones. | Choose a source with compatible zone type, material and active physics. | Boundary conditions and face closures |
| Select All / Deselect All | Selects or clears all compatible destination zones in the copy dialog. | No effect until the copy/apply action is executed. | Review the selected destination list before applying a bulk copy. | Boundary conditions and face closures |