Note

Go to the end to download the full example code.

Harmonic acoustic analysis#

This example examines a harmonic acoustic analysis that uses surface velocity to determine the steady-state response of a structure and the surrounding fluid medium to loads and excitations that vary sinusoidally with time.

Import necessary libraries#

import os

from PIL import Image
from ansys.mechanical.core import App
from ansys.mechanical.core.examples import delete_downloads, download_file
from matplotlib import image as mpimg
from matplotlib import pyplot as plt
from matplotlib.animation import FuncAnimation

Embed mechanical and set global variables

app = App()
app.update_globals(globals())
print(app)

cwd = os.path.join(os.getcwd(), "out")


def display_image(image_name):
    plt.figure(figsize=(16, 9))
    plt.imshow(mpimg.imread(os.path.join(cwd, image_name)))
    plt.xticks([])
    plt.yticks([])
    plt.axis("off")
    plt.show()

Ansys Mechanical [Ansys Mechanical Enterprise]
Product Version:242
Software build date: 06/03/2024 09:35:09

Configure graphics for image export#

Graphics.Camera.SetSpecificViewOrientation(ViewOrientationType.Iso)
image_export_format = GraphicsImageExportFormat.PNG
settings_720p = Ansys.Mechanical.Graphics.GraphicsImageExportSettings()
settings_720p.Resolution = GraphicsResolutionType.EnhancedResolution
settings_720p.Background = GraphicsBackgroundType.White
settings_720p.Width = 1280
settings_720p.Height = 720
settings_720p.CurrentGraphicsDisplay = False
Graphics.Camera.Rotate(180, CameraAxisType.ScreenY)

Download geometry and materials files#

geometry_path = download_file("C_GEOMETRY.agdb", "pymechanical", "embedding")
mat_path = download_file("Air-material.xml", "pymechanical", "embedding")

Import the geometry#

geometry_import = Model.GeometryImportGroup.AddGeometryImport()
geometry_import_format = (
    Ansys.Mechanical.DataModel.Enums.GeometryImportPreference.Format.Automatic
)
geometry_import_preferences = Ansys.ACT.Mechanical.Utilities.GeometryImportPreferences()
geometry_import_preferences.ProcessNamedSelections = True
geometry_import.Import(
    geometry_path, geometry_import_format, geometry_import_preferences
)


GEOM = Model.Geometry

solid1 = GEOM.Children[0]
solid2 = GEOM.Children[1]
solid3 = GEOM.Children[2]
solid4 = GEOM.Children[3]
solid5 = GEOM.Children[4]
solid6 = GEOM.Children[5]
solid7 = GEOM.Children[6]
solid8 = GEOM.Children[7]
solid9 = GEOM.Children[8]
solid10 = GEOM.Children[9]
solid11 = GEOM.Children[10]

solid1.Suppressed = True
solid2.Suppressed = True
solid3.Suppressed = True
solid4.Suppressed = True
solid5.Suppressed = True
solid7.Suppressed = True
solid10.Suppressed = True
solid11.Suppressed = True


app.plot()
harmonic acoustics

Store all Variables necessary for analysis#

MESH = Model.Mesh
NS = Model.NamedSelections
CONN = Model.Connections
CS = Model.CoordinateSystems
MAT = Model.Materials

Setup the Analysis#

Add harmonic acoustics and unit system

Model.AddHarmonicAcousticAnalysis()
ExtAPI.Application.ActiveUnitSystem = MechanicalUnitSystem.StandardMKS

Import and assign materials

MAT.Import(mat_path)
solid6.Material = "Air"
solid8.Material = "Air"
solid9.Material = "Air"

Create coordinate system

LCS1 = CS.AddCoordinateSystem()
LCS1.OriginX = Quantity("0 [mm]")
LCS1.OriginY = Quantity("0 [mm]")
LCS1.OriginZ = Quantity("0 [mm]")
LCS1.PrimaryAxisDefineBy = CoordinateSystemAlignmentType.GlobalZ

Generate mesh

MESH.ElementSize = Quantity("200 [mm]")
MESH.GenerateMesh()

Create named selections#

SF_Velo = Model.AddNamedSelection()
SF_Velo.ScopingMethod = GeometryDefineByType.Worksheet
SF_Velo.Name = "SF_Velo"
GEN_CRT1 = SF_Velo.GenerationCriteria
CRT1 = Ansys.ACT.Automation.Mechanical.NamedSelectionCriterion()
CRT1.Active = True
CRT1.Action = SelectionActionType.Add
CRT1.EntityType = SelectionType.GeoFace
CRT1.Criterion = SelectionCriterionType.Size
CRT1.Operator = SelectionOperatorType.Equal
CRT1.Value = Quantity("3e6 [mm^2]")
GEN_CRT1.Add(CRT1)
CRT2 = Ansys.ACT.Automation.Mechanical.NamedSelectionCriterion()
CRT2.Active = True
CRT2.Action = SelectionActionType.Filter
CRT2.EntityType = SelectionType.GeoFace
CRT2.Criterion = SelectionCriterionType.LocationZ
CRT2.Operator = SelectionOperatorType.Equal
CRT2.Value = Quantity("15000 [mm]")
GEN_CRT1.Add(CRT2)
SF_Velo.Activate()
SF_Velo.Generate()

ABS_Face = Model.AddNamedSelection()
ABS_Face.ScopingMethod = GeometryDefineByType.Worksheet
ABS_Face.Name = "ABS_Face"
GEN_CRT2 = ABS_Face.GenerationCriteria
CRT1 = Ansys.ACT.Automation.Mechanical.NamedSelectionCriterion()
CRT1.Active = True
CRT1.Action = SelectionActionType.Add
CRT1.EntityType = SelectionType.GeoFace
CRT1.Criterion = SelectionCriterionType.Size
CRT1.Operator = SelectionOperatorType.Equal
CRT1.Value = Quantity("1.5e6 [mm^2]")
GEN_CRT2.Add(CRT1)
CRT2 = Ansys.ACT.Automation.Mechanical.NamedSelectionCriterion()
CRT2.Active = True
CRT2.Action = SelectionActionType.Filter
CRT2.EntityType = SelectionType.GeoFace
CRT2.Criterion = SelectionCriterionType.LocationY
CRT2.Operator = SelectionOperatorType.Equal
CRT2.Value = Quantity("500 [mm]")
GEN_CRT2.Add(CRT2)
ABS_Face.Activate()
ABS_Face.Generate()

PRES_Face = Model.AddNamedSelection()
PRES_Face.ScopingMethod = GeometryDefineByType.Worksheet
PRES_Face.Name = "PRES_Face"
GEN_CRT3 = PRES_Face.GenerationCriteria
CRT1 = Ansys.ACT.Automation.Mechanical.NamedSelectionCriterion()
CRT1.Active = True
CRT1.Action = SelectionActionType.Add
CRT1.EntityType = SelectionType.GeoFace
CRT1.Criterion = SelectionCriterionType.Size
CRT1.Operator = SelectionOperatorType.Equal
CRT1.Value = Quantity("1.5e6 [mm^2]")
GEN_CRT3.Add(CRT1)
CRT2 = Ansys.ACT.Automation.Mechanical.NamedSelectionCriterion()
CRT2.Active = True
CRT2.Action = SelectionActionType.Filter
CRT2.EntityType = SelectionType.GeoFace
CRT2.Criterion = SelectionCriterionType.LocationY
CRT2.Operator = SelectionOperatorType.Equal
CRT2.Value = Quantity("4500 [mm]")
GEN_CRT3.Add(CRT2)
PRES_Face.Activate()
PRES_Face.Generate()

ACOUSTIC_Region = Model.AddNamedSelection()
ACOUSTIC_Region.ScopingMethod = GeometryDefineByType.Worksheet
ACOUSTIC_Region.Name = "ACOUSTIC_Region"
GEN_CRT4 = ACOUSTIC_Region.GenerationCriteria
CRT1 = Ansys.ACT.Automation.Mechanical.NamedSelectionCriterion()
CRT1.Active = True
CRT1.Action = SelectionActionType.Add
CRT1.EntityType = SelectionType.GeoBody
CRT1.Criterion = SelectionCriterionType.Type
CRT1.Operator = SelectionOperatorType.Equal
CRT1.Value = 8
GEN_CRT4.Add(CRT1)
ACOUSTIC_Region.Activate()
ACOUSTIC_Region.Generate()

Analysis settings#

ANALYSIS_SETTINGS = Model.Analyses[0].AnalysisSettings
ANALYSIS_SETTINGS.RangeMaximum = Quantity("100 [Hz]")
ANALYSIS_SETTINGS.SolutionIntervals = 50
ANALYSIS_SETTINGS.CalculateVelocity = True
ANALYSIS_SETTINGS.CalculateEnergy = True
ANALYSIS_SETTINGS.CalculateVolumeEnergy = True

Boundary conditions and load#

HARM_ACOUST = Model.Analyses[0]

Acoustic region

Acoustic_region = [x for x in HARM_ACOUST.Children if x.Name == "Acoustics Region"][0]
Acoustic_region.Location = ACOUSTIC_Region

Surface velocity

SURF_VEL = HARM_ACOUST.AddAcousticSurfaceVelocity()
SURF_VEL.Location = SF_Velo
SURF_VEL.Magnitude.Output.DiscreteValues = [Quantity("5000 [mm s-1]")]

Acoustic pressure

ACOUST_PRES = HARM_ACOUST.AddAcousticPressure()
ACOUST_PRES.Location = PRES_Face
ACOUST_PRES.Magnitude = Quantity("1.5e-7 [MPa]")

Acoustic absoption surface

ABSORP_SURF = HARM_ACOUST.AddAcousticAbsorptionSurface()
ABSORP_SURF.Location = ABS_Face
ABSORP_SURF.AbsorptionCoefficient.Output.DiscreteValues = [Quantity("0.02")]

HARM_ACOUST.Activate()
Graphics.Camera.SetFit()
Graphics.ExportImage(
    os.path.join(cwd, "bounday_conditions.png"), image_export_format, settings_720p
)
display_image("bounday_conditions.png")
harmonic acoustics

Add results#

SOLN = Model.Analyses[0].Solution

Acoustic pressure

ACOUST_PRES_RES1 = SOLN.AddAcousticPressureResult()
ACOUST_PRES_RES1.By = SetDriverStyle.ResultSet
ACOUST_PRES_RES1.SetNumber = 25

Acoustic velocity - total and directional

ACOUST_TOT_VEL1 = SOLN.AddAcousticTotalVelocityResult()
ACOUST_TOT_VEL1.Frequency = Quantity("50 [Hz]")

ACOUST_DIR_VEL1 = SOLN.AddAcousticDirectionalVelocityResult()
ACOUST_DIR_VEL1.Frequency = Quantity("50 [Hz]")
ACOUST_DIR_VEL1.CoordinateSystem = LCS1

ACOUST_DIR_VEL2 = SOLN.AddAcousticDirectionalVelocityResult()
ACOUST_DIR_VEL2.NormalOrientation = NormalOrientationType.ZAxis
ACOUST_DIR_VEL2.By = SetDriverStyle.ResultSet
ACOUST_DIR_VEL2.SetNumber = 25

Acoustic sound pressure and frequency bands

ACOUST_SPL = SOLN.AddAcousticSoundPressureLevel()
ACOUST_SPL.Frequency = Quantity("50 [Hz]")

ACOUST_A_SPL = SOLN.AddAcousticAWeightedSoundPressureLevel()
ACOUST_A_SPL.Frequency = Quantity("50 [Hz]")

ACOUST_FRQ_BAND_SPL = SOLN.AddAcousticFrequencyBandSPL()

A_FREQ_BAND_SPL = SOLN.AddAcousticFrequencyBandAWeightedSPL()

Z_VELO_RESP = SOLN.AddAcousticVelocityFrequencyResponse()
Z_VELO_RESP.NormalOrientation = NormalOrientationType.ZAxis
Z_VELO_RESP.Location = PRES_Face
Z_VELO_RESP.NormalOrientation = NormalOrientationType.ZAxis

Acoustic kinetic and potentional energy frequency response

KE_RESP = SOLN.AddAcousticKineticEnergyFrequencyResponse()
KE_RESP.Location = ABS_Face
KE_display = KE_RESP.TimeHistoryDisplay

PE_RESP = SOLN.AddAcousticPotentialEnergyFrequencyResponse()
PE_RESP.Location = ABS_Face
PE_display = PE_RESP.TimeHistoryDisplay

Acoustic total and directional velocity

ACOUST_TOT_VEL2 = SOLN.AddAcousticTotalVelocityResult()
ACOUST_TOT_VEL2.Location = PRES_Face
ACOUST_TOT_VEL2.Frequency = Quantity("30 [Hz]")
ACOUST_TOT_VEL2.Amplitude = True

ACOUST_DIR_VEL3 = SOLN.AddAcousticDirectionalVelocityResult()
ACOUST_DIR_VEL3.NormalOrientation = NormalOrientationType.ZAxis
ACOUST_DIR_VEL3.Location = PRES_Face
ACOUST_DIR_VEL3.Frequency = Quantity("10 [Hz]")
ACOUST_DIR_VEL3.Amplitude = True

ACOUST_KE = SOLN.AddAcousticKineticEnergy()
ACOUST_KE.Location = ABS_Face
ACOUST_KE.Frequency = Quantity("68 [Hz]")
ACOUST_KE.Amplitude = True

ACOUST_PE = SOLN.AddAcousticPotentialEnergy()
ACOUST_PE.Location = ABS_Face
ACOUST_PE.Frequency = Quantity("10 [Hz]")
ACOUST_PE.Amplitude = True

Solve#

SOLN.Solve(True)

Messages#

Messages = ExtAPI.Application.Messages
if Messages:
    for message in Messages:
        print(f"[{message.Severity}] {message.DisplayString}")
else:
    print("No [Info]/[Warning]/[Error] Messages")

[Warning] One or more Contact Regions are connected to Acoustic Physics Regions. To improve the solution, the contact settings may have been overwritten internally.  Refer to the notes for Acoustics Analysis in the Help System for more details.

Postprocessing#

Total acoustic pressure#

Tree.Activate([ACOUST_PRES_RES1])
Graphics.ExportImage(
    os.path.join(cwd, "acou_pressure.png"), image_export_format, settings_720p
)
display_image("acou_pressure.png")
harmonic acoustics

Total acoustic velocity#

Tree.Activate([ACOUST_PRES_RES1])
Graphics.ExportImage(
    os.path.join(cwd, "totalvelocity.png"), image_export_format, settings_720p
)
display_image("totalvelocity.png")
harmonic acoustics

Sound pressure level#

Tree.Activate([ACOUST_SPL])
Graphics.ExportImage(
    os.path.join(cwd, "sound_pressure.png"), image_export_format, settings_720p
)
display_image("sound_pressure.png")
harmonic acoustics

Total velocity on pressure surface#

Tree.Activate([ACOUST_TOT_VEL2])
Graphics.ExportImage(
    os.path.join(cwd, "totalvelocity_pressure.png"), image_export_format, settings_720p
)
display_image("totalvelocity_pressure.png")
harmonic acoustics

Kinetic energy on absorption face#

Tree.Activate([ACOUST_KE])
Graphics.ExportImage(
    os.path.join(cwd, "kineticenergy.png"), image_export_format, settings_720p
)
display_image("kineticenergy.png")
harmonic acoustics

Total acoustic pressure animation#

animation_export_format = (
    Ansys.Mechanical.DataModel.Enums.GraphicsAnimationExportFormat.GIF
)
settings_720p = Ansys.Mechanical.Graphics.AnimationExportSettings()
settings_720p.Width = 1280
settings_720p.Height = 720

ACOUST_PRES_RES1.ExportAnimation(
    os.path.join(cwd, "press.gif"), animation_export_format, settings_720p
)
gif = Image.open(os.path.join(cwd, "press.gif"))
fig, ax = plt.subplots(figsize=(16, 9))
ax.axis("off")
img = ax.imshow(gif.convert("RGBA"))


def update(frame):
    gif.seek(frame)
    img.set_array(gif.convert("RGBA"))
    return [img]


ani = FuncAnimation(
    fig, update, frames=range(gif.n_frames), interval=200, repeat=True, blit=True
)
plt.show()