| Author | Message | ||
     shohel mahmud (smahmud) New member Username: smahmud Post Number: 2 Registered: 09-2003 |
Hi there My problem is related to interaction of sound wave to thermal field. I developed my model one dimensional differential equations for velocity and temperature fluctuations in combined time and spatial domain. Then I assumed the fluctuation of any variables (say velocity U)as U=U0+U1*exp(i*w*t), where U0 is a mean (constant ) component and w is the circulr frequency, i is square root of -1. The final euqations are in space domain only but have imaginary number with it. I found some help in the help manue of FlexPDE shown below: Help-FlexPDE Help 3.0-Technical Notes-Applications in Electromagnetic-V. Harmonic Analysis and -VIII. Specialization of the harmonic equations The problem is those equations have still the imaginary number 'i'. Can I solve my problem keeping this 'i' (flexpde can recognise this i) or there is other process to handle this type of situation. In help menu nothing is said about this. Thank you very much. Shohel | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 69 Registered: 06-2003 |
FlexPDE cannot treat complex variables directly. Each variable and each equation must be real. A complex variable is therefore represented by two VARIABLES, the real part and the imaginary part. There are two equations, one for the real part and one for the imaginary part. When you expand your equations with the complex exponential, expand the exponential into the real cosine term and the imaginary sine term. There will then be real terms and imaginary terms in the equation. Segregate the real terms into the real equation, and the imaginary terms into the imaginary equation, and remove the "i". |