Attenuation unit, dBm or dB/cm 回答済み

5件のコメント

• 正式なコメント

  

  Chloe Allison

  2018年10月11日 09:12

  Hello Ahmad,

  Since OnScale's default units are meters you should define attenuation in dB/m as you have in your example.You have also defined the power-law power loss correctly. I have changed a few things in your code, mainly in your watnl definition - bovera pmax pcut must be defined on a new line. This is not currently described in the command reference which we will change.

  matr
  wvsp on
  type tisu
  prop watnl 1000 1482 0 0.01 0.0 0.0
  5 -2e+08 2e+08
  sdmp watnl 6e6 db 0.217 0 1e6 2
  thrm watnl 4180 0.6 0.6 0.6
  end

  
  matr
  wvsp on
  type elas
  prop LDPE 930 2080 0 0.01
  vdmp LDPE 6e6 db 400 0 1e+06 1
  thrm LDPE 2100 0.33 0.33 0.33
  end

  
  matr
  wvsp on
  type elas
  prop air 1.24 343 0
  end

  Best Regards,

  Team OnScale.

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• 

  Ahmad

  2018年10月11日 21:34

  Thanks Chloe. It was a great help. In case I run the script in PZFlex on my PC (not OnScale), is my definition of attenuation in dB/m still correct?

  Thanks again.

  Ahmad

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• 

  Chloe Allison

  2018年10月12日 08:24 (編集済み 2018年10月12日 08:24)

  Ahmad,

  PZFlex also works in dB/m so you can use this material definition.

  Best Regards,

  Team OnScale.

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• 

  Ahmad

  2018年10月16日 19:27

  Thanks for your response.

  I tried to run the model using

  symb #get { step } timestep
  symb simtime = 2 * ( ( $x3 - $x2 ) / $velmin )
  symb nexec = nint ( $simtime / $step )
  symb nloops = 40
  symb nexec_loop = nint ( $nexec / $nloops )
  
  proc plot save
  exec $nexec_loop

  I adjusted the function to be a continuous sine wave and the simulation time as 2 * ( ( $x3 - $x2 ) / $velmin ) to just consider for the wave travel inside material 2, which is (x3-x2), reach the back surface and get reflected until the reflected wave reaches the front surface of this material. I derived the loss and used that in the thermal script to derive the temperature rise. As I increased the simulation time (e.g. 3 * ( ( $x3 - $x2 ) / $velmin ), or 4 * ( ( $x3 - $x2 ) / $velmin ) ), I expected to see more temperature rise in material 2 as more energy was deposited. As I expected, the loss was increased by increasing the simtime, but the temperature rise in material 2 decreased by increasing the simtime. Would you please let me know if it is reasonable to get lower temperature rise, while the loss is increasing? Is it possible to send you the acoustic and thermal codes?

  Thank you for your help.

  Ahmad

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• 

  Kevin Chan

  2018年10月23日 12:38

  Typically, the loss will accumulate under CW drive so we would expect temperature to build increase over time. Thermal simulations are usually a 2 stage model: acoustic model to determine the losses (simulation typically in milliseconds) for X number of cycles and a separate temperature simulation to apply the loses over a long simulation period (typically in seconds)

  If you are only using a single model, what you may be seeing is that your temperature simulation is not running for any substantial amount of time to capture any meaningful increase in temperature.

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