Fluent 边界条件意义

当计算密度可变的非稳态流动时，即使采用的是不可压缩流模型也不能 用

outflow

边界

d.

多相流模型不可用

outflow

边界，唯一例外是明渠模型（

open chennel

）

vent

边界：

用于定义入口的损失系数、入口周围环境的总压和温度

.

fan

进气风扇边界：

< br>用于定义一个外部进气风扇，其压力突变量（

pressure jump

）、

流动方向、周围环境总压和温度需要被定义。

vent

边界：

用于定义出口 的损失系数、入口周围环境的总压和温度

.

t fan

边界：

用于定义一个外部排气风扇，其压力突变量（

< br>pressure jump

）、流动

方向、周围环境总 压和温度需要被定义。

The inlet and exit boundary condition options in ANSYS FLUENT are as follows:

ty inlet boundary conditions are used to define the velocity and scalar properties of the

flow at inlet boundaries.

re

inlet

boundary

conditions

are

used

to

define

the

total

pressure

and

other

scalar

quantities at flow inlets.

flow inlet boundary conditions are used in compressible flows to prescribe a mass flow

rate at an inlet. It is not necessary to use mass flow inlets in incompressible flows because when

density is constant, velocity inlet boundary conditions will fix the mass flow. Like pressure and

velocity inlets, other inlet scalars are also prescribed.

re outlet boundary conditions are used to define the static pressure at flow outlets (and

also other scalar variables, in case of backflow). The use of a pressure outlet boundary condition

instead

of

an

outflow

condition

often

results

in

a

better

rate

of

convergence

when

backflow

occurs during iteration.

re

far-field

boundary

conditions

are

used

to

model

a

free- stream

compressible

flow

at

infinity,

with

free-stream

Mach

number

and

static

conditions

specified.

This

boundary

type

is

available only for compressible flows.

w

boundary

conditions

are

used

to

model

flow

exits

where

the

details

of

the

flow

velocity and pressure are not known prior to solution of the flow problem. They are appropriate

where the exit flow is close to a fully developed condition, as the outflow boundary condition

assumes

a

zero

streamwise

gradient

for

all

flow

variables

except

pressure.

They

are

not

appropriate for compressible flow calculations.

vent boundary conditions are used to model an inlet vent with a specified loss coefficient,

flow direction, and ambient (inlet) total pressure and temperature.

fan

boundary

conditions

are

used

to

model

an

external

intake

fan

with

a

specified

pressure jump, flow direction, and ambient (intake) total pressure and temperature.

vent

boundary

conditions

are

used

to

model

an

outlet

vent

with

a

specified

loss

coefficient and ambient (discharge) static pressure and temperature.

t fan boundary conditions are used to model an external exhaust fan with a specified

pressure jump and ambient (discharge) static pressure.

二、“完全发展流动（

fully developed flow

）”的概念

流动是“层流” 还是“紊流”（或者“湍流”）是由流体的粘性，密度，流动速度和管

径大小来决定的。

所以一旦你的流体物理性质确定，

流速大小和管径确定，

流动状态就确定

了。比如你的问题中，流动状态只能为湍流。