Defining an incident wave interaction property

From the main menu bar, select InteractionPropertyCreate.

In the Create Interaction Property dialog box that appears, do the following:

• Name the interaction property. For more information about naming objects, see Using basic dialog box components.

• Select the Incident wave type of interaction property.

Click Continue to close the Create Interaction Property dialog box.

In the Speed of sound in fluid field, enter the sound speed in fluid, $c_f$.

In the Fluid density field, enter fluid mass density, ${\rho }_f$.

From the Definition field, choose the type of wave to define the incident wave property.

• Select Planar to specify a planar incident wave.

• Select Spherical to specify a spherical incident wave.

• Select Diffuse to specify a field of planar waves incident from multiple angles.

• Select Air blast to specify air blast loading on structures using the CONWEP model.

• Select Surface blast to specify surface blast loading on structures using the CONWEP model.

If you are specifying a spherical incident wave, select the propagation model. For more information, see Describing incident wave loading.

• Select Acoustic to specify an incident wave in which the amplitude is inversely proportional to the distance from the source.

• Select UNDEX charge to specify UNDEX bubble data.

• Select Generalized decay to specify spatial decay of the incident wave field.

If you selected the UNDEX charge propagation model, click the Physical, Material, and Bubble Model tabs and specify the following values:

Physical Data

• Ratio of specific heats for gas, $\gamma$.

• Acceleration due to gravity, g.

• Atmospheric pressure, $p_{atm}$.

• Flow drag coefficient, $C_D$.

• Flow drag exponent, $E_D$.

• Toggle on Neglect wave effects in fluid and gas to neglect the wave effects.

Material Data

• Charge material constant, K.

• Charge material constant, k.

• Charge material constant, A.

• Charge material constant, B.

• Adiabatic charge constant, $K_c$.

• Density of charge material, ${\rho }_c$.

• Mass of charge material, $m_c$.

Bubble Model Step Data

• Time duration, $T_{\mathrm{final}}$.

• Maximum number of time steps for the bubble simulation, $N_{\mathrm{steps}}$. The bubble amplitude simulation ceases when the number of steps reaches $N_{\mathrm{steps}}$ or the time duration, $T_{\mathrm{final}}$, is reached.

• Relative step size control parameter, ${\mathrm{\Omega }}_{\mathrm{rel}}$.

• Absolute step size control parameter, $X_{\mathrm{abs}}$.

• Step size control exponent, $\beta$. The step size, $\mathrm{\Delta }t$, is decreased or increased according to the error estimate: ${\left({\mathrm{\Omega }}_{\mathrm{rel}}\left|x\right|+X_{\mathrm{abs}}\right)}^{\beta }\le \mathrm{\Delta }t{\left|\frac{dx}{dt}\right|}^{\beta }$.

If you selected the Generalized decay propagation model, enter values for the dimensionless constants A, B, and C, where $A>-1$, $B>-1$, and $C\ge 0$.

If you are defining a diffuse incident wave, specify the seed number in the Seed number field for the diffuse source calculation.

If you selected the Air blast or Surface blast definition, specify the following settings in the CONWEP Charge portion of the dialog box:

• In the Equivalent mass of TNT field, specify the equivalent mass of TNT in any preferred mass unit.

• In the Conversion for mass to kilograms field, specify a multiplication factor to convert the preferred mass unit to kilograms.

• In the Conversion for length to meters field, specify a multiplication factor to convert the analysis length unit to meters.

• In the Conversion for time to seconds field, specify a multiplication factor to convert the analysis time unit to seconds.

• In the Conversion for pressure to pascals field, specify a multiplication factor to convert the analysis pressure unit to pascals.

Click OK to create the incident wave interaction property and to exit the editor.