COMSOL Multiphysics - Multiphysics Modeling

COMSOL Model Report

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1. Table of Contents

2. Model Properties

PropertyValue
Model name 
Author 
Company 
Department 
Reference 
URL 
Saved dateNov 24, 2006 11:05:27 PM
Creation dateNov 17, 2006 4:07:23 PM
COMSOL versionCOMSOL 3.3.0.405

File name: D:\research\ASA Talks\f06\animations\visualizations\diffraction\barrier h=lambda.mph

Application modes and modules used in this model:

3. Constants

NameExpressionValueDescription
f025 frequency
x02  
y02  
c0200 speed of sound m/s
rho01.21  
p01  
t01/f0  
lambda0c0/f0  
h08 height of barrier
holh0/lambda0 ratio of height to lambda

4. Global Expressions

NameExpressionDescription
gt(t<2*t0)*(-8*pi^2*f0^2*(t-t0)*exp(-pi^2*f0^2*(t-t0)^2))gaussian source 
gtssin(2*pi*f0*t)sinusoidal source 
gtccos(2*pi*f0*t)cosine source 

5. Geometry

Number of geometries: 1

5.1. Geom1

geometry_section0

5.1.1. Point mode

geometry_section0_0_img

5.1.2. Boundary mode

geometry_section0_1_img

5.1.3. Subdomain mode

geometry_section0_2_img

6. Geom1

Space dimensions: 2D

Independent variables: x, y, z

6.1. Mesh

6.1.1. Mesh Statistics

Number of degrees of freedom14816
Number of mesh points3758
Number of elements7300
Triangular7300
Quadrilateral0
Number of boundary elements216
Number of vertex elements12
Minimum element quality0.701
Element area ratio0.001

mesh_section_0_0

6.2. Application Mode: Pressure Acoustics (acpr)

Application mode type: Pressure Acoustics (Acoustics Module)

Application mode name: acpr

6.2.1. Scalar Variables

NameVariableValueDescription
p_ip_i_acprexp(-1/2*(t-x/cs_acpr)^2/0.01^2)Incident pressure wave
p_refp_ref_acpr20e-6Pressure reference

6.2.2. Application Mode Properties

PropertyValue
Default element typeLagrange - Quadratic
Analysis typeTransient
DampingOff
Specify eigenvalues usingEigenfrequency
Solve forTotal wave
Symmetry plane x=0Off
Symmetry type for x=0Symmetry
Symmetry plane y=0Off
Symmetry type for y=0Symmetry
FrameFrame (ref)
Weak constraintsOff

6.2.3. Variables

Dependent variables: p

Shape functions: shlag(2,'p')

Interior boundaries not active

6.2.4. Boundary Settings

Boundary 1, 32
Type Radiation conditionRadiation condition
Pressure source (p0)Pa00
Inward acceleration (nacc)m/s200
Source location, x coordinate (x0)m22
Source location, y coordinate (y0)m224
wavetype1PLCYL

Boundary4-678
TypeSound hard boundary (wall)Radiation conditionRadiation condition
Pressure source (p0)000
Inward acceleration (nacc)000
Source location, x coordinate (x0)4174
Source location, y coordinate (y0)484
wavetypeCYLCYLPL

Boundary9-12
TypeNormal acceleration
Pressure source (p0)10*cos(2*pi*f0*t)
Inward acceleration (nacc)1*cos(2*pi*f0*t)
Source location, x coordinate (x0)0
Source location, y coordinate (y0)0
wavetypePL

6.2.5. Subdomain Settings

Subdomain 1
Fluid density (rho)kg/m3rho0
Speed of sound (cs)m/sc0

7. Solver Settings

Solve using a script: off

Analysis typeTransient
Auto select solverOn
SolverTime dependent
Solution formAutomatic
Symmetricauto
AdaptionOff

7.1. Direct (UMFPACK)

Solver type: Linear system solver

ParameterValue
Pivot threshold0.1
Memory allocation factor0.7

7.2. Time Stepping

ParameterValue
Times0:0.005:0.25
Relative tolerance0.01
Absolute tolerance0.0010
Times to store in outputSpecified times
Time steps taken by solverFree
Manual tuning of step sizeOff
Initial time step1E-3
Maximum time step1E-3
Maximum BDF order2
Singular mass matrixMaybe
Consistent initialization of DAE systemsBackward Euler
Error estimation strategyInclude algebraic
Allow complex numbersOff

7.3. Advanced

ParameterValue
Constraint handling methodElimination
Null-space functionAutomatic
Assembly block size5000
Use Hermitian transpose of constraint matrix and in symmetry detectionOff
Use complex functions with real inputOff
Stop if error due to undefined operationOn
Type of scalingAutomatic
Manual scaling 
Row equilibrationOn
Manual control of reassemblyOff
Load constantOn
Constraint constantOn
Mass constantOn
Damping (mass) constantOn
Jacobian constantOn
Constraint Jacobian constantOn

8. Postprocessing

post_0

9. Variables

9.1. Point

NameDescriptionExpression
Lp_acprSound pressure level10 * log10(0.5 * p_t_acpr * conj(p_t_acpr)/p_ref_acpr^2)
Lp_s_acprScattered sound pressure level10 * log10(0.5 * p_s_acpr * conj(p_s_acpr)/p_ref_acpr^2)
p_t_acprTotal acoustic pressurep
p_s_acprScattered pressure wavep-p_i_acpr

9.2. Boundary

NameDescriptionExpression
na_acprNormal accelerationnx_acpr * ax_acpr+ny_acpr * ay_acpr
nk_acprScalar product between n and kdir(kdirx_acpr * nx_acpr+kdiry_acpr * ny_acpr)/sqrt(kdirx_acpr^2+kdiry_acpr^2)

9.3. Subdomain

NameDescriptionExpression
ax_acprLocal acceleration, x component-(px-qx_acpr)/rho_acpr
ay_acprLocal acceleration, y component-(py-qy_acpr)/rho_acpr
Lp_acprSound pressure level10 * log10(0.5 * p_t_acpr * conj(p_t_acpr)/p_ref_acpr^2)
Lp_s_acprScattered sound pressure level10 * log10(0.5 * p_s_acpr * conj(p_s_acpr)/p_ref_acpr^2)
p_t_acprTotal acoustic pressurep
p_s_acprScattered pressure wavep-p_i_acpr
norma_acprLocal acceleration, normsqrt(abs(ax_acpr)^2+abs(ay_acpr)^2)
normq_acprDipole source, normsqrt(abs(qx_acpr)^2+abs(qy_acpr)^2)