Random Number Generator and manufacturing defects

[Andrew Oldfield]

Hi everyone,

where is the randomness from the Random Number Generator incorporated into the model?

I specifically want to look at how variation in the degree of manufacturing defects in mirrors will impact the flux on the receiver, and am unsure if I need to define a reflective surface that incorporates a stochastic error function, or if am able to use the error function to simulate this (even if it meant writing new source).

Regards,

Andrew

[Manuel J. Blanco]

Dear Andrew,

Variation in the degree of manufacturing defects which translates into small scale variations of the real shape of the reflecting surface with regard to its ideal shape can be modelled by modifying the m_sigmaSlope property of the specular material used in the corresponding surface ShapeKit. This property represent the overall sigma slope of the reflecting surface, in milliradians, excluding the effect of the sunshape, which is specified elsewhere in Tonatiuh. 

For a short overview of how to model errors in solar concentrators using statistical parameters you can read section 

8.4.3 The Contribution of Errors of Chapter 8 Concentrator Optics of the online book "Power From The Sun". Another useful reference to understand optical error modelling using statistical parameters is an 1978 Sandia National Labs document entitled "The Helios Model for the Optical Behavior of Reflecting Solar Concentrators", you can download the document in pdf form here.

I hope the above information is useful. Thanks for using Tonatiuh and for sharing your questions about the program in this forum.

Best regards,

Manuel