Solution dialog box (Acoustics BEM)

Solution
Name	Specifies the name of the solution.
Solver	Specifies the solver for the solution.
Analysis Type	Specifies the analysis type.Direct Acoustic — The acoustic fluid is present on the exterior side of the boundary element mesh to simulate exterior radiation, or on the interior side to simulate interior noise propagation. The direct BEM analysis works only on closed geometries where the boundary forms a simple closed surface without holes, openings, or stiffening ribs.Indirect Acoustic — The acoustic fluid can be present on both sides of the boundary element mesh. The indirect BEM analysis can handle interior and exterior radiation simultaneously, and it allows you to analyze a wide variety of geometries, including geometries that contain holes and openings, as well as T-shaped stiffening ribs.Indirect Vibro-Acoustic — The acoustic fluid can be present on both sides of the boundary element mesh and includes fluid-structure interaction by transferring structural vibrations to the acoustic domain.For more information see, Acoustics BEM solver environment.
Solution Type	Specifies the solution type.Acoustic Response — Appears when the analysis type is set to Direct Acoustic or Indirect Acoustic. Computes the results for the acoustic model.Acoustic Transfer Vector — Appears when the analysis type is set to Indirect Acoustic. Computes the acoustic transfer vector, which is a simplified representation of an acoustic fluid.Vibro-Acoustic Response — Appears when the analysis type is set to Indirect Vibro-Acoustic. Computes the acoustic response of a vibrating structural surface interacting with an acoustic fluid.
Automatically Create Step or Subcase	Appears when the solution type is set to Acoustic Response or Vibro-Acoustic Response.Creates a step or subcase automatically.
Subcase and Boundary Condition Creation
These options are available only when the solution is created from a load recipe.Subcase and Boundary Condition Creation settings define the subcase type and the boundary condition type to be created in the Simulation Navigator.
Subcase Type	Specifies the solution step for the BEM analysis, for example:Subcase - Acoustic Response — Available only for Direct Acoustic and Indirect Acoustic BEM analysis.Subcase - Vibro-Acoustic Response — Available only for Indirect Acoustic BEM analysis.You can add one or more subcases to the solution. The subcases define the loads in the solutions.
Hierarchy Type	Specifies the type of boundary condition to be created.Aggregated — An aggregated boundary condition reduces the number of objects created in the Simulation Navigator, which improves the creation and update time of the load recipe based solutions.Aggregated boundary conditions are not editable.
Information	Displays information about the boundary condition support for each mapped load type parameter in the load recipe, based on the current configuration of the solution.
Acoustic Response, Acoustic Transfer Vector, or Vibro-Acoustic Response
Preview	Opens the Information window and shows the contents of the solver input file.
Indirect Acoustic Model Formulation
Appears when the Analysis Type is set to:Indirect Acoustic and the solution type to Acoustic Response.Indirect Vibro-Acoustic and the solution type to Vibro-Acoustic Response.
Model Formulation	Specifies the following model formulation method.StandardFast MultipoleH-MatrixFor more information see, Solution formulation methods for indirect acoustic analysis (Acoustics BEM).
Frequency Definition
Forcing Frequencies	Specifies the forcing frequencies.Create Forcing Frequencies — Opens the Modeling Objects Manager dialog box where you can create the forcing frequencies.For more information, see Define forcing frequencies (Acoustics BEM).
Output Requests
Appears when the solution type is set to any solution except Acoustic Transfer Vector.
Output Requests	Specifies the output request for the solution.Select an existing output request from the list or click Create Modeling Object to create a new output request.Click Edit to edit the selected output request.For more information, see Requesting output for Acoustics BEM analysis and Request output for Direct Acoustic, Indirect Acoustic, and Indirect Vibro-Acoustic analysis types (Acoustics BEM).
Use Result of Acoustical Element Side	Appears when the analysis type is set to Indirect Acoustic or Indirect Vibro-Acoustic. Specifies the acoustic element side on which to compute the results.Top — Computes the acoustic results on the top (positive) side.Bottom — Computes the acoustic results on the bottom (negative) side.Note: Top (positive) side and Bottom (negative) side are defined by the element normal.
Quadrature
You set the Accuracy Level as Standard, Fine, Coarse, or Custom.
	Specifies the quadrature distance parameters in the solution.The boundary elements in near, middle, and far field regions are defined by the ratio D/L where:D = Distance between the two boundary element centersL = Average element edge lengthYou can define the following quadrature parameters in the solution. You set the two parameters (a = Near-mid and b = Mid-far) to define the regions as follows:Near-Mid Field Boundary RatioFor near-mid area ratio (a), a >= 0.Mid-Far Field Boundary RatioFor mid-far area ratio (b), 0 <= a <= b.Near Field QuadratureIf 0 <= D/L <= a, the two elements or faces are in the near field of each other.Middle Field QuadratureIf a < D/L <= b, the two elements or faces are in the medium field of each other.**Far Field Quadrature**If D/L > b, the two elements or faces are in the far field of each other.For more information, see Controlling accuracy of the numerical integration with quadrature settings (Acoustics BEM).	Near-Mid Field Boundary Ratio	For near-mid area ratio (a), a >= 0.	Mid-Far Field Boundary Ratio	For mid-far area ratio (b), 0 <= a <= b.	Near Field Quadrature	If 0 <= D/L <= a, the two elements or faces are in the near field of each other.	Middle Field Quadrature	If a < D/L <= b, the two elements or faces are in the medium field of each other.	Far Field Quadrature	If D/L > b, the two elements or faces are in the far field of each other.
Near-Mid Field Boundary Ratio	For near-mid area ratio (a), a >= 0.
Mid-Far Field Boundary Ratio	For mid-far area ratio (b), 0 <= a <= b.
Near Field Quadrature	If 0 <= D/L <= a, the two elements or faces are in the near field of each other.
Middle Field Quadrature	If a < D/L <= b, the two elements or faces are in the medium field of each other.
Far Field Quadrature	If D/L > b, the two elements or faces are in the far field of each other.
Number of Overdetermination Points
As % of Acoustical Nodes	Appears when the analysis type is set to Direct Acoustic.Specifies the over determination points as a percentage of acoustical nodes to be added to the collocation points.The direct boundary element method solves the Kirchhoff-Helmholtz equation by discretising the surface. The interior of the radiating body is not described mathematically and in the frequency spectrum irregular frequencies (a non-uniqueness problem) can be observed in the solution. These frequencies are physically not explained, as they are only mathematical artifacts. To overcome the problem, the system of equations can be enlarged by adding overdetermination points, which are placed inside the acoustic volume. Overdetermination points will improve the quality of the results.The drawback is that since the geometry may be complicated, the exact location of the overdetermination points is not explicitly known, so more points than necessary have to be added for a stable solution. For each added overdetermination point the system matrices are increased by one dimension, which will increase the number of equations to be solved and result in longer solution times.
Vibro-Acoustic Coupling
Fluid-Structure Interface Modeling Parameters	Appears when the analysis type is set to Indirect Vibro-Acoustic.Specifies the vibro-acoustic coupling for the solution.Select an existing fluid-structure interface modeling parameters from the list or click Create Modeling Object to create new fluid-structure interface modeling parameters.Click Edit to edit the selected fluid-structure interface modeling parameters.For more information, see Define fluid-structure interface modeling parameters (Acoustics BEM).
Fast Multipole Method Parameters
These options appear when Model Formulation is set to Fast Multipole.
Normalized Residual	Specifies the normalized residual value for the whole calculation.For more accuracy you can reduce the normalized residual value up to 1.0e-5, but this requires more iterations and therefore is less efficient to solve.
Maximum Number of Iterations	Sets the maximum number of iterations. The maximum iterations limit the computing time.Note: You can set the minimum number of iterations as zero.
Convection Effect
These options appear when the analysis is Indirect Acoustic and the Model Formulation is set to Fast Multipole or H-Matrix.
Include Mean Flow Effect	Lets you specify the uniform mean flow velocity and the orientation of the fluid flow.
Flow Velocity	Available when the Include Mean Flow Effect check box is selected.Specifies the flow velocity.
Orientation	Specifies a vector orientation to indicate the direction of the flow.
Specify Vector	Available when the Include Mean Flow Effect check box is selected.Specifies the flow direction.For more information, see Vector dialog box.To reverse the direction of the vector, click Reverse Direction .
Job Control
Run Job in Foreground	Runs the job in foreground.
Sharp Corner Detection
Enable Sharp Corner Detection	Appears when the analysis type is set to Direct Acoustic.Enables sharp corner detection on the mesh boundary.If the model boundary contains sharp corners, duplicate normal vectors will exist between element edges. In a Direct BEM solution sharp corners on the boundary affect the solution accuracy because each boundary node must have a unique normal vector to compute the acoustic boundary condition.Sharp corner with non-unique normal vectors****Corner node duplicated to create unique normal vectorsWhen you use Sharp Corner Detection, you specify the Max Normal Angle (the included angle between the boundary vectors), to find the sharp corners. The software then creates duplicate nodes and disconnects the element edges at the corner to create unique normal vectors. Post processing properly displays the results at any new nodes that are duplicated by this process.	Sharp corner with non-unique normal vectors	Corner node duplicated to create unique normal vectors
Sharp corner with non-unique normal vectors	Corner node duplicated to create unique normal vectors
Max Normal Angle	Appears when you select the Enable Sharp Corner Detection check box.Specifies the angle between non-unique normal vectors. When non-unique normal vectors are found then duplicate nodes are created during the solution.

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Fluid-Structure Interface Modeling Parameters dialog box (Acoustics BEM)

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Solution dialog box (Acoustics BEM), Simcenter 3D 2021.1 Series

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