Note that through the use of commenting, the problem can be presented in a structured format where the given information and knowns are segregated from the equations and unknowns.Comments 0 Log in to post a comment Document transcript ME 259 - IHT: Interactive Heat Transfer Computer Exercises 1.
Basic Equation Solving Suppose you wish to solve the following set of equations, where q 1, q 2, q 3, and T are unknowns: q 1 0.35(1000 - T) q 2 5.67 10 - 8 (T 4 - 300 4 ) q 3 1.4(T - 300) 43 q 1 q 2 q 3 Note that two equations are nonlinear and the system cannot be solved analytically. STEP 1 - Preprocessing Simply type the equations as given onto the IHT workspace as shown below. You may insert comments or headings by preceding text lines with a dou ble slash or by bracketing long sections of text with.. Nonlinear Equation System Example q1 0.35(1000 - T) q2 5.67E - 08(T4 - 3004) q3 1.4(T - 300)(43) q1 q2 q3 STEP 2 - Solving Click the Solve button to prepare the solver. If your equations have syntax errors, an error warning will appear - click OK and usually the solver will highlight the word or equation that contains the error. If you do not supply enough equations for the number of unknowns, another error warning will appe ar - click OK and a summary of equations and unknowns will appear to help you determine what is missing. If there are no syntax or number of equations errors, an Initial Guesses table appears. Initial guesses are required for each unknown and the solver uses a value of 1 as a default guess. You may change these guesses, however, the default values are often satisfactory. You may also insert Minimum and Maximum solution values if you know the range of possible solution values. ![]() ![]() Note: if a previous dataset exists, the solver will ask you whether you want to save it or discard it.) If the message Equation set successfully solved appears in the Data Browser, then the values for q1, q2, q3, and T represent a valid solution. In general, there may exist several valid solution sets for a system of nonlinear equations. The particular solution found by the solver depends upon the initial guesse s and the search algorithm. In this example, only one valid solution set exists since the equations are based upon a physical problem: T 322.1 q1 237.3 q2 150.7 q3 86.59 STEP 3 - Postprocessing Once a valid solution has been found, you may want to copy it to the clipboard for pasting. Highlight the solution by clicking the upper left rectangle in the table and then click Copy. Options are available for transposing rowscolumns and including variable names. It is suggested that you paste your solution to the bottom of your equation worksheet before printing a hardcopy. This is done by locating the cursor at the bottom and then clicking Paste from the Edit menu. Also, be sure to type in appropriate units next to each solution value. You can now print your entire problem by clicking Print from the File menu. If you wish to have greater control of how your page looks in terms of font stylesize, organization, bolditalicunderline, etc., copy and paste your entire worksheet to Notepad or Microsoft Word. Perf orming parametric studies and plotting results are possible using the Explore and Graph functions. These features will be used in the next example. Iht Software How To Set UpSolving a Heat Transfer Problem: Insulated Steam Pipe Undergoing Convection and Radiation The following worksheet example shows how to set up a typical heat transfer problem.
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