Lecture 3

Advanced Features in EES

By

Mary shanti

Emai:mpampa1@lsu.edu

Phone:389-2963

Department of mechanical Engineering

Louisiana State University

Advanced Features in EES

• Integration and Differential Equations• Table-based integral function

• Equation-based integral function

• Build-in Functions• Mathematical functions

• String functions

• Thermophysical property functions

Integral Function

• EES has a function called INTEGRAL function which can be used to evaluate an integral and solve differential equations.

• The format of integral function is

2

1

t

tdt)t(f)t,f(Intergral

Two Basic Forms of Integral Function

• There are two basic forms of the integral function:

• Table-based integral function

• Equation-based integral function

Table-based integral function

• Table-based Integral function uses the Parametric table to provide the limits and step size of the integration variable.

• The integral variable, t, • must be a legal variable name

• has values defined in one of the columns of the table

• The integrand, f, can be a variable or expression of variables, values, and t.

Equation-Based Integral Function

• Equation-based integral function does not require the use of Parametric table.

• The format is • F=Integral(f, t, t1, t2, tStep)

• or F=Integral(f, t, t1, t2), where t1 and t2 are the lower an upper limits of the integration variable, tStep is the increment EES will use for the integration. If tStep is not provided, EES will use automatic step size.

Differential Equations

Any kind of first order differential equations

can be rewritten as

Where y0 is the initial value of y

),( yxfdx

dy

dxyxfyy ),(0